Along with the "how do we stop young men turning into angry radical right-wing types" discourse there's been a lot of discourse about the need for cishet male allies of the cause to stand up to their racist, sexist, homophobic etc. male friends and tell them to stop being those things, and other people saying "I've tried that and it doesn't really work, they just call me a fag and then stop hanging out with me."
And yeah, given that the left and right are more divided than ever it is kind of strange to assume that a male feminist is going to be hanging out with a bunch of sexist dudebros who will take it to heart when they make a rape joke and he says, "dudes...that was fucked up." That's not how it works.
(Also, yes, I realize that "the right" and "sexist dudebros" are not really the same thing but there's an area of overlap that is specifically being focused on in a lot of this discourse.)
I've been in sort of the Mirror World version of that scenario: being in heavily left-wing spaces, hearing people say fucked up shit about men and being the one who says, "uh that's kinda fucked up why would you say something like that?" and can confirm, yes, this kind of pushback does not work in that context. They just ridicule you and double down on whatever they were saying. Pushing out dissenting voices is a time-honored bonding ritual for these types of groups.
On the other hand, when I am alone with an actual friend, someone I care about who also cares about me, and they say something fucked up and I respond with shocked silence or a quiet "hey now," they usually backpedal pretty quickly.
So I guess if you're trying to stop someone from going down a rabbit hole my advice is not to confront them in a group setting or online where other people can witness the confrontation, especially if you are in a setting where most onlookers are likely to side with them. Talking to them alone, and in a less confrontational way, is what actually gets results.