I mean, the last point is weird. They'd never say that, and do not care about the illusion of being open.

Point 1 is true.

Point 2, what makes you think federation will make millions of users want to move away, or even know folk are on another service. They'll probably censor the word lemmy and every lemmy address to avoid folk advertising away. The fediverse will just be filled with nonsense data and they'll pull the stuff that helps their platforms and keeps people hooked on the teet. Without that data, they may not be at critical mass to sustain Threads and it might eventually die. With that and Twitter going to pot, avoiding federation actually helps Mastodon as it provides a distinguishable separate entity that has reached critical mass and has significant good will with the user base that motivates them to keep sharing content.