Yes — exactly! Your colleague’s perspective is convenient (for him and others like him) but not very logical. First of all, the way that someone learns something is to be tested. If you say, “I know how to fly an airplane” but have never been off the ground, it’s moot. Second, rape (and most harassment) isn’t about lust — it’s about power and dominance exerted through the weapon of sex. That’s why little babies, old nuns and straight men all get raped.
I’m glad your boss spoke to him. I too am grateful for all of the allies who already get all of this stuff or who are beginning to. We need every single one of them!