My thoughts is that it’s a simple situation really. If they’re harassing or assaulting people, the women will call the cops or something, simple situation and get the guy arrested. If he’s not doing anything, it’s nothing harmful. Apparently that’s not a solid enough answer. What should I have said?
You made a mistake.
You engaged with someone that wasn’t asking in good faith. The idea itself is so stupid that snagging engaging with it isn’t worth the time and effort.
The only useful response to that question is “are you really that stupid, or do you think I am?”