I sympathize with you for having to deal with a player like that. Oh, if he wants to hate women, that's his right, as it is ours to condemn him for it; however, trying to force the way the conversation unfolded, just to rub it in, was a bridge too far in my opinion.
That being said, I think we dehumanize men and infantilize women when we regard violence against women as worse than, rather than equal to, violence against men. And I think we do a disservice to women when we say that women need to be protected from the portrayal of fantasy violence perpetrated against women, as it is just another way of saying that women are weaker than men, who do not require that protection. I hope we can agree that violence against anyone is bad, and that women do not require special protections based on reasons that are destined to be inherently insulting to women.
Fantasy violence is what it is. I can enjoy winning dark side rolls without revealing myself as, or becoming, a monster. While the player in question clearly enjoyed the pistol-whipping for his own hateful reasons, there is nothing about the action itself that is inherently worse than the endless killing or torturing of either gender we do in this game. (I'd be interested in seeing how often we are able to torture or beat up men in this game compared to women. I'd actually be impressed if there wasn't a sizable difference in gender representation in such scenarios.)
By the way, you know what else isn't really funny (when looked at objectively, because society clearly considers it to be funny, much like a certain thing that happens to men in prison all the time), and is exceptionally painful when it occurs? A kick to the groin. And yet it's celebrated in the game with its own skill