"White men already know not to shoot people. We don't need to teach them not to."
And yet, somehow, ALL of the school shootings have been done by white dudes. Not women, not minorities. If the problem were solely "criminals are going to criminal", then you'd see other demographics committing mass shootings, too. Criminals will break the law, that is true. No matter how much you teach people to not do things, some will continue to do them. That does not preclude the fact that sometimes we can do a better job of teaching people not to do something. As an example: littering. Some people are going to litter, no matter what. However, you can teach people to litter less, as the "Don't Mess With Texas" campaign proved.
"We need to teach men to accept 'no'" is a true statement. "Some men will refuse to accept 'no', even if you do a better job teaching them." is also a true statement. The two are not contradictory.