So this was an encounter with (If my research is correct) one Matthew J. Carroll-Schmidt, who styles himself MJCS on Facebook.  He's allegedly a lawyer.
I had no idea who he was.  He was at Archon, dressed as Space Ghost, and we conversed cordially for about ten minutes about random stuff until he noticed my badge.
Him: "Hey, are you Michael Williamson, the racist guy?"
Me: "Er, huh?"
Him: "Yeah, I'm MJCS.  Do you know me?"
Me: "I don't think so."  
Him: "I think we talked on Facebook."
Me: "Possibly.  I have 3500 followers on Facebook.  I talk to a lot of people."
Him: "Do you know Tim Bolgeo?"
Me: "Slightly."
Him: "Yeah, it is you, you racist piece of shit."
On visual observation, he appeared to be an overweight, out of shape, middle class, middle aged white male with a small penis (He was dressed as Space Ghost, and the spandex does not lie).
(Try to contain your surprise.)
Which of course perfectly qualifies him as an expert on racism.
This individual is apparently the overweight, out of shape, middle class, middle aged white male with a small penis who shit his panties on Twitter about an out of context comment from Tim's fanzine, call Tim a racist, and got thousands of other members of the Butthurt Little Bitch Brigade to shit their panties, to a point where the concom was forced to uninvite Tim to avoid the deluge of leftist feces. This greatly annoyed a lot of us, who know Tim well. There were discussions where we presented facts and lefticle panty-shitters called us "racists."  Even those of our side who were black.
There were even leftist ignoranuses (that's a person who's ignorant and an asshole) asking why the con would invite someone who publishes a "racist ezine," thus demonstrating that they had no knowledge of the events whatsoever, but were outraged anyway.  
His e-zine is about science (Tim being a retired nuclear engineer), space, SF, people in the SF community needing help, and a few jokes, some of them tacky.  He'll even take jokes about Italian Catholics, even though he's one himself.  But of course, humor is lost on leftists.
I asked, "Are you aware that [well known black author] made statements supporting Tim Bolgeo?"
"Yes."
"So are you claiming to know more about racism than [well known black author]?"
"Yes. I read his [Tim's] blog." [Actually, it's an ezine.]
Aha!  I think we found the racist in the equation.  Obviously that poor black author doesn't know real racism when he sees it.  He needs an overweight, out of shape, middle class, middle aged, racist white male with a small penis to whitesplain it to him.
He continued, "Yeah, so you're a racist piece of shit. A racist piece of shit.  A racist piece of shit."
Clearly, MJCS is a low-Q specimen as well as a low-T specimen.
Now, there are five reasons why it's a really bad idea to loudly and publicly call someone a "racist piece of shit."
First, they might actually be one, and proud of it.  In which case, they'll be pleased with your comment and you accomplish nothing.
Second, they might be one, and not aware of it, in which case, you've negated any possibility of reasonable discussion to persuade them otherwise, and accomplished less than nothing.
Third, it's probably slander, and you might get your ass sued. A competent lawyer would know this.
Fourth, if it's not true, you're pissing someone off needlessly, and they might…
Fifth, beat the living shit out of you and kick your teeth down your throat, especially if you're an overweight, out of shape, middle class, middle aged, racist white male with a small penis.  Actually, ANY of them might do it, and given the provocation, quite a few bystanders might cheer them on.
I chose to ignore this and not get violent.  It was clearly what he wanted, so he could file a lawsuit, sort of like a fourth-rate cousin of his fellow Democrat Fred Phelps. Though to be fair, despite his laundry list of flaws, Phelps was not a racist.
But, I think I might contact the Bar Assn about this behavior. It certainly lent nothing to the dignity of the profession.
Of course, he was assuming a punch or slap and a bruise for a lawsuit.  What he might get is his face smashed into the table and his teeth kicked down his throat, some broken ribs and fingers.  After all, if you're getting arrested, it may as well be for something worthwhile.  If this ever does happen to him, I hope there's a Youtube video.
He then said, "Yeah, so, I know it's an article of faith among your racist subculture that I wouldn't be here. Well, HERE I AM!"
Wow.  Here you are.  Fighting racism by dressing as a white character at a convention that's 95% white people, attacking people with verbal epithets. You should be so proud.
Honestly, I'd completely forgotten he existed.  Twittards are plentiful and my time is valuable.  I pay them no heed.
I'm not sure how he knows so much about any subculture I might belong to, seeing as he seemed blissfully unaware I'm a relatively well-known author in SF, was a convention Guest this year, a Special Guest last year, and have a substantial body of work. Also, I'm a member of three minority groups myself and have a mixed-race wife. I just don't wave the flag about it and call people names over it. (It's perfectly okay for me to call him names, since as an apparent overweight, out of shape, middle class, middle aged, racist white male with a small penis, he's part of the racist culture America fosters, a privileged member of the dominant ethnic group, and fair game by those of us with less privilege.  Also, he had macro-aggressed me.)
I'm not sure how he knows so much about a racist subculture. I know very little about them myself, and even have to ask for help deciphering some of the slang they use, when I read it online.  However, since as best I recall he'd publicly stated he wasn't going to attend, my peer group assumed he wasn't.  We had concluded that if he did show up he'd be an overweight, out of shape, middle class, middle age white male with a small penis, and it appears we were right!
Bonus point: I bet that within five exchanges, he'd reveal himself to be a racist, and either suffering guilt or in denial about it, and I appear to have been correct about that, too.
So I reported the harassment to the concom, who called security and had him informed to stop harassing me.
It turned out he'd been at the convention feedback session, loudly decrying it as an "unsafe space" for women, even though none of the women I know report that.  In fact, they reported feeling very safe.  But, I'm sure as an apparent overweight, out of shape, middle class, middle age white male with a small penis, he knows more about sexism than they do, and can mansplain it to them.
Then, he'd claimed to be a lawyer and demanded details of their incorporation documents, presumably to use it for further leverage against them. That would make him a shit lawyer, since such information is publicly available about a non-profit corporation.  Unless he was doing it for purposes of harassing them, in which case he's a piece of shit lawyer.  But then, what other kind would an overweight, out of shape, middle class, middle aged, racist white male with a small penis who works for "Activist groups" be?  
One of the groups appears to be the "Nonhuman rights project," securing civil rights for animals, or perhaps for people who think they're animals. Such group appears to have accomplished nothing. Otherwise, a search shows no real papers, no real cases, not much of anything. Exactly what you'd expect of an "activist" who's an overweight, out of shape, middle class, middle aged, racist white male with a small penis.
I suggested that they might consider uninviting him for future events, since his presence seems to be disruptive and make quite a few people feel unsafe.  Also, by reducing attendance by one apparent overweight, out of shape, middle class, middle aged, racist white male with a small penis, they'd improve the racial and gender diversity slightly. Not to mention the smell.
This, by the way, is why you should NEVER respond to a Twit-shitstorm.  It only validates people who should have none.
In conclusion, MJCS, you apparent overweight, out of shape, middle class, middle aged, racist white male with a small penis, take this as my warning not to ever approach my personal space ever again, or I will regard it as assault and respond accordingly.
Oh, by the way, there's no need to apologizeΓÇöthe head of the concom did so on your behalf, since civil behavior is beyond your emotional capability. There was no need of him to do so, but he understands manners and civil behavior.
