The context to this is saying about how they're not a fan of the subreddit LeftWingMaleAdvocates, which is a bad subreddit, it's mostly just anti-feminist and basically just MRA, but they just call themselves left-wing. Most of their "left-wing" stuff is actually just "classical liberal" talking points, so they are bad, but calling them tankie is ridiculous.
Fetterman could legit just go, "yeah I'm a tankie" :gigachad-hd: and destroy any negative connotations the term had instantly