He obviously thought there was no problem making such a comment, because the environment he inhabits is populated by other men who think the same. When you challenged him, he felt threatened, hence the “first amendment rights” comment (totally normal thing to say…) and unending pushback. Hopefully it will sink in over time, but you’ll have to accept that you’ve done all you can with this one.
It is horrible to be put on the spot by someone with a totally inappropriate statement. I find it uncomfortable because I just don’t know what to say in response – 1. It’s weird, 2. “Making a fuss” could be used against me.