...Are you sure you are old enough to be using this site, my man?
But in all seriousness: "Tumblr resident" refers to a specific type of internet shitheads who (pretty obviously) used to frequent Tumblr, back when that crappy site was still "a thing." And of course they would be the kind of lunatics raving non-stop about social issues such as feminism, gay rights, etc., except
not in a sensible or progressive manner, instead just calling for the genocide of men to empower women (no, really, many of them actually did that) and other insane stuff along those lines.
So kind of like Rachel there, except somehow
way more extreme in most cases. And they all "got away with it" because of Tumblr's
complete lack of moderation. Hence the term! Tune in next time for more boring internet history with me!
-Mal