What if the guy played a black dude that mugged everybody, and says he's just playing in character? There's some stuff you just don't DO, and that's about the magnitude of what I saw several times at the con.
-blarg
If he's accurately playing a black guy who is a mugger- say, as commonly depicted in movies or on CSI, CSI Miami, CSI NY, Law & Order, Law & Order SVU, Law & Order Criminal Intent, NYPD Blue, The Shield, Homicide: Life on the Streets, Hill Street Blues, COPS, Jail, Lockup, your nightly news, Investigative Reports, Without a Trace, Criminal Minds, Cold Case, Cold Case Files, 90% of gangsta rap videos, or or some other show that nobody's ever heard of

- I don't think I'd have a problem with it.
If, OTOH, he was playing a black guy who was a mugger who played up other stereotypes- the watermelon/fried chicken/corn on the cob eating, joint/crack smoking, bug eyed with fear, and all that other stuff you can see in Spike Lee's
Bamboozled- alongside with the mugger stereotypes, I might have a problem.
The difference?
1) You can actually find actual actors of integrity willing to portray the former, not the latter. Some black actors make quite the comfortable living forever playing Mugger #3.
2) There are real black muggers out there- I know, I've taken the testimony of one or two in my day- but
none was
every stereotype you ever saw about blacks.