Earlier quoted context omitted.
I see zero trouble as long as it requires no additional identification, no additional payment, and no mandatory time limit for the sideloaded apps. That is, fine by me. I can wait for 24 hours once in a few years when I acquire a new mobile phone.
You are thinking about it from the point of view of an enthusiast/hacker who wants to put their homebrew stuff on it. But this is also tightening around developers who may want to distribute their applications to lay users.
Users who use F-Droid are already not as lay. If you distribute stuff that Play Store would ban, your users are likely not as lay, too.
Yes, it's inconvenient, but I see it as a good-faith attempt to limit exposure of lay users to scams, not some power grab.