Every liberal does it too, from center right radlibs to far-right "conservatives": the most extreme right fringe liberals hate the mainstream liberals for not being bigoted enough, the mainstream libs hate the radlibs for not being cruel enough, and the radlibs hate the left for not being chauvinist enough.
Denouncing chauvinism in particular is like a liberal moral event horizon, a cardinal sin against their self-interested belief in the righteousness of the imperial hegemon that keeps the treats flowing at gunpoint.
The thing about social issues is that they change by society. In certain cultures where I live, it's normal for cis women to be addressed as 'dude'. The term is considered gender neutral by default in those circles, and I wouldn't be surprised if it was increasingly recuperated in more youth spaces.
It's obviously different if someone uses it in a gendered context (e.g. 'a dude', 'i fuck dudes'), that's offensive and horrible to misgender with, and obviously it's a dumbass gamble to assume it will be received as neutral when talking with new people. And, of course, this doesn't excuse the moron who plays the "I have a friend who is fine with me saying this" routine. But what that user said isn't as absurd as it may sound, because there are legitimate societies, some which are my day-to-day life even, where it already is neutral.