Their point might be that "sexism" is misogyny, that negative attitudes toward men aren't equivalent to the very deliberate oppression of women, that the enforcers of men's oppression tend to be men. Comments like that from the post aren't nice and I don't care to defend it, but it's somewhat equivalent to a marginalized person making a snarky comment at those who benefit from their oppression, calling it sexist isn't accurate if we're discussing systemic oppression (which generally we are whenever women come up).

That said I don't know this user, for all I know they're just reactionary lol