Hangover 2 Cast: Heroes or Hypocrites?

Last night news broke that Mel Gibson's cameo had been cut from The Hangover 2 after the cast and crew protested his involvement. As a commenter pointed out, convicted rapist Mike Tyson appeared in the first film, without a peep. Were the Hangover guys justified in wanting Gibson off the film, or did they take principle too far? Would you still work with him?