There is no way “EEE” is applicable here outside of spreading FUD. The biggest risk to the Fediverse isn’t Meta, it’s other Fediverse users.
The collective fediverse’s userbase is nothing more than a rounding error to Meta. They probably have to delete a magnitude or two higher number of spam accounts each day.
Threads is 50x the size of the Fediverse and is growing significantly faster. Twitter users are almost certainly their priority.
Meta is probably only using this as a way to convince regulators they don’t need regulation and so some director can put “changed the world” on their resume.
If anything, it’s easier to pull people over because their friends who refuse Mastodon/etc aren’t holding them back.
And the absolute worst case? Meta ends up contributes junk to the ActivityPub protocol or Mastodon, the community forks it, software gets patched to adopt the intricacies of whatever changes are needed to defang whatever controversial stuff gets added in, and everything carries on.
The most realistic concern is the communities that provide a safe space for those regularly subject to harassment online may start getting unwanted attention from trolls. After all, this expands the potential audience from 2 million to 100+ million.