Caught him reading an MRA site

How? He was either doing it on a work device, in which case he's actually an idiot, or he was doing it on a personal device, and if everything else said in this story is true he wouldn't have let you anywhere near him.

overheard him telling the truth

Again, how? Anyone with two brain cells who (rightfully) believes that the vast majority of women are hired for affirmative action because they're a special class also realizes that they're not allowed to mention that women are only hired for affirmative action because they're a special class.

It's like saying you work in big banking and you caught one of the hedge fund managers complaining that, "Man, there sure are a lot of jews." Everyone who knows about it and has an issue with it also knows that there's no way they're allowed to complain about it in a work setting (or even work-adjacent).