Bullshit. He doesn't want to make longer videos, not because people would leak them, but rather because longer videos imply he would have to be actually doing something in them (masturbation, cumshots, et cetera) and he doesn't want to do anything sexual on camera, either because of his ideological views or because his boyfriend doesn't let him. That's the actual reason
That...isn't completely true though. You've already mentioned that on 4chan it was only popularized as a meme. People who look only laugh at femboy memes or jerk off to some femboy doujins vs. people actually self identifying as femboys are two completely different groups of people. I'd still be more inclined to believe the majority of actual femboys are more left leaning.
You can believe that but a lot of that just isn't true. I say this as someone who's interacted with many over the years. Many femboys are young, it's really common amongst youth especially ones that are terminally online to be gay(actually gay or prison/pornsick gay) and nazi, and like darkwaifu, often nazbol. Yes it's hypocritical and weird, but it's the stupidity of youth for you. I'm not saying left leaning ones don't exist, they do, but they're a minority and a good portion of them end up becoming trans. While yes, there's no actual data and thus any conclusions are purely subjective and anecdotal, and thus one could only speak from experience, I have to say, out of the thousands upon thousands I've interacted with many are like that. It's hard to believe but the "I'm one of the good ones" and "this won't happen to me" runs deep amongst delusional people on both ends, and youth on both ends of that spectrum tend to be pretty damn delusional, especially if they're dressing up as girls for guys or themselves to cum to. Also many things that come from 4chan and people start to legitimately believe and even base their time and lives around started as a meme. It's just how the internet and terminally online/gullible people work.
Ong like Homelander said "you guys are the real heroes"