There are extreme ideological distinctions between Facebook and Tumblr that you're ignoring. Suggesting ideology only came into it with Trump and that the Threads pushback was about the spectre of a competitor's popularity is very strange. As is the "Fedi admins are petty, but not me, a Fedi admin" commentary. People had well-founded and widely varied concerns about Meta joining the fediverse. It had nothing to do with wanting to remain in obscurity; just about every fedi user I've ever encountered is absolutely begging everyone on social media to join.

> The Fediverse's structure is already a lot more centralized than anyone would like to admit

Hi, I'm "anyone", and: no it isn't? Technically and philosophically, no it isn't. Large instances are not a failure of decentralisation, because as you evidently know, their existence does not preclude you or anyone else setting up a server and federating. There's no universe in which "scaling the network" reduces decentralisation, in fact it's the solution to the "fuck Matt Mullenweg" situation you speculate about. The less homogenous fedi admins become, the more the network is sustained by people who don't even know who he is. Your comment is rife with generalisations about the motivations of people on the fediverse, but it's far less monolithic than you think.