Yeah stuff is public, but that doesn’t mean we have to hand it to them on a silverplatter and allow them to scrape it legally. Because they don’t have the legal right to just scrape websites, as everything is copyrighted unless the ToS specifically allows federated instances to copy it. By defederating you make it pretty clear they they are not allowed to just take it.
Next point equally dumb: no one owns the fediverse, sure. But if enough instances say no, that means they are not welcome. Democracy and all…
And the last point is the dumbest: Threads will just include a revenue sharing model like Youtube does and the ”dumb fucks" (quote Zuckerberg) will love to include ads in their posts; even praise Meta for being so generous to throw them some crumbs.