Your saying that if they were talking about real rape, that would be awful, but since they were just comparing the similarities between winning a basketball game and rape, there was nothing awful about it? Say, just like when a left-wing-nut compared Bush to Hitler, or a right-wing-nut compares Obama to Hitler, there is no stigma attached, it's just a metaphor?
Comparing winning basketball to rape trivializes rape, in the same way comparing Bush/Obama to Hitler trivializes Hitler. The difference is that Hitler is gone, but rape is something people face every day.
I think you have it backwards.
The rape is being used to elevate a rather meaningless sports win into something more, a brutal act of dominance. One has to acknowledge the brutality of rape in order for the metaphor to work.