People's opinions and what they say have weight and actually affect people (not to mention they affect people's actions). He isn't defending pineapple on pizza, he's defending the victimization of women.
Whether or not this case crosses it there clearly is a line where expressing an opinion isn't okay. If he was spouting off racist stuff you would have very few people defending him being fired.
Being racist goes beyond having an opinion. I’m talking about what is clearly a much more limited viewpoint, about a specific situation. Racism is deeply held, applies (by definition) incredibly broadly, and is reasonably expected to affect how you treat coworkers.
Whether or not this case crosses it there clearly is a line where expressing an opinion isn't okay. If he was spouting off racist stuff you would have very few people defending him being fired.