LOL, Glory!
It's true, I don't think they would have wanted him in drag.
HOwever, it wasn't a picture of their characters- it was a picture of the actors. None of them are dressed as their characters; they were dressed as themselves. Now, granted, they were told what to wear, but that's beside the point. Rosario does not look like a stripper, Tracie does not have the butch look them seem to be going for for this Joanne... the only one who looks a bit like his character is Taye in the suit. Which he's so sexy in, why put him in anything else?

But, since their not really dressing as their characters, there's no reason for Wilson to be in drag. :P
"I mean, how many of us could honestly say that at one time or another he hasn't set fire to some great public building?"