You aren't wrong, but you are treating Slowbeef as a regular "twitch streamer" and a regular "Youtuber". Most of his audience, most of his followers (26k on Twitter, 40k youtube, 19k on twitch) are a video game audience and he produces (or produced) video game content. His stream is video game content - he should be able to regularly convert more than 0.05% of his followers into viewers. Not just his audience, either, but he's also on a Twitch team with other larger draws as well (HerrDekay has ~350 viewers right now during the day). He's been a guest/feature/exposed to several other incredibly large audiences over nearly a decade - he doesn't have "normal" visibility.
Even if he doesn't stream for huge amounts of time - he's a partnered streamer with nearly a decade of visibility, with teams and access to much wider audiences, and a somewhat consistent streaming schedule - he should be able to drive much more of his audience into his content and realistically he doesn't. Go for the side hustle, (266 subs translates to roughly $665 dollars a month, on top of the $284 patreon bucks) but 266 subs is horrendous for him.
EDIT - I don't care if he streams, but having such a low participation rate with such a large audience indicates that most people don't care if he streams either.