There's only a certain number of times you can say "RETARDS R STUPEID LOL" before the premise gets played out, and this game is a perfect example of that. I'm not even going to get into whether it's ethical or not, because there's no point.
But the main, glaring problem with this game is that it's just not fun. Given the premise, you could've made some sort of shoot-'em-up or at least given it some non-linear action. You instead chose to make stupidly easy shooting sequences mixed in with moronic retard jokes we've all heard before.
TL;DR: offensive jokes are fine, but they're NOT a substitute for actual gameplay.