One last attempt, then I'll let it be. If men aren't able to see discrimination against women and women aren't able to see discrimination against men, then neither side would be able to tell whether they are being discriminated against or being treated differently than the other sex. It is a humorous philosophical point that points out flaw in your view. Men don't need to become women in order to recognize sexism, otherwise we could never see our faults and would blindly have to trust the other's word on it. No one could ever reject the charge of sexism made by the other sex. People accustomed to pedantic argument would have picked up on his challenge, others won't so it's not a big deal.
There is a difference in saying sexism occurs and sexist culture exists. There are always jacka$$es, period. Discrimination will always exist, and it isn't always a bad thing. The question isn't whether or not there is some cretin out there who will try to kiss Cajun on the cheek. There is now and there always will be. But the point is that now, no one likes that guy and everyone knows he's an a$$. He's the exception, not the rule. The real question of sexism is whether women are purposefully being excluded because of the fact that they are women, and whether they have less opportunity as men. We are well beyond the point where that was the case. Just go look at any of the application sites for major airlines (as I posted above) or recruiting posters for the military. It's a joke. If anyone is being discriminated against, it is white men. There is a reason every airline application asks for your sex and race, and it isn't to get more white men on board. I've been around aviation for a long time and I haven't encountered many black women pilots, actually none that I can remember off the top of my head. But, if you were to look at pilot recruitment sites you would have to assume that they make up 25% of the pilot field. There are a lot of reasons why black women aren't pilots in large numbers, but racism and sexism isn't one of them to any significant degree. Cajun can say some guy tried to kiss her on the cheek, I can say my application is less likely to get pulled because I'm a white man. But the fact is we both still have the opportunity to achieve what we want to achieve. Life isn't totally fair, but in America it's a lot more fair that most anywhere else.