They call that an "Ad Hominem" attack. Like when the liberals say "I seen a person with a Palin bumper sticker on their car and I think they should be drug out of their car and beat to death". And I say "What the f is wrong with you? What would make you say something like that?" They pull that Ad Hominem card like Obama pulls the race card in defense of their horrible statement. Yeah, like there is something seriously f'd up in my head to ask that. Compared with them saying someone should be beat for having a bumper sticker.
But you are right. Their is no reason to avoid the obvious that a person saying this tragedy is racist or anything else crazy. One should make sure the person saying such things is not totally crazy for agreeing with them even if its to humor them.