Men are socialized in the US to be extremely narcissistic, and only really consider their own feelings. The kind of men who were being the loudest and most incredulous in this conversation were also the kind of men who don't have empathy for men either. They don't have empathy for anyone but themselves. They only understand how they would personally feel if they were sexually assaulted; no one else.
And since they have no idea what that's like, have ever experienced it, or likely ever will, they think they know enough. They don't take into account the years of trauma in its wake.