Tropic Thunder: Offensive or No?

Yesterday, my mom forwarded me an email asking that I participate in a boycott of the movie Tropic Thunder, based on the fact that it contains disparaging remarks about the mentally disabled -- specifically, several uses of the word "retard" or "retarded," as well as a character who is an actor who plays a mentally disabled person in a film within the film called "Simple Jack." Now, my brother has Prader-Willi Syndrome, and my mother is very involved with the PWSA (I'm guessing that's where this email came from), so obviously I'm neither tolerant of nor an advocate of throwing around offensive terms and using people with disabilities as the butt of a bunch of dumb jokes -- but even as I read this email, I found myself becoming more and more skeptical. The thing is, context is key. I don't approve of humor that is truly offensive and ignorant, but I'm also wary of becoming so overly-sensitive to particular words that we come to overlook the context and fixate upon the words themselves. An ordinary, well-adjusted adult calling another ordinary, well-adjusted adult "retarded" is offensive. A character who is clearly ignorant and meant to be disliked calling a character who is mature and well-adjusted "retarded" is farcical commentary -- and it makes the ignorant character look bad, not the other way around. In this situation, the use of the term serves to expose such remarks as offensive and uncalled for, rather than to be offensive and uncalled for in its own right. Truthfully, based on this email I read, the main question I had when I got to the end was whether the person who wrote it had actually seen the movie, or just heard through the grapevine that these words were used -- because there was virtually no attempt to discuss the tone or context surrounding the remarks, and without that, the information is useless. (On a side note, considering that the person who wrote the email got the movie's title wrong -- he/she called it Tropical Thunder instead of Tropic Thunder -- I'm guessing he/she hadn't seen the movie... *grin*)

( Words, words, words... (cut for length) )