I doubt that is the plan. The Fediverse is tiny, even after the recent growth. Prior to June it was basically just Mastodon, and I doubt Meta is agile enough to start this from scratch in response to the June growth. This is a lot of effort to take down a competitor that’s widely considered to be rough around the edges, and is only just now hitting 2m active monthly users.

Realistically Threads has been in the works for a while as a way to eat Twitter’s market share while Twitter destroys itself. I suspect they see value in the ActivityPub protocol in the same way Yahoo saw value in email in the 90s. Regardless of whether EEE is their intention or not, Meta’s presence in the Fediverse is going to have major implications for its long term stability.

EDIT: on further reflection, I suspect the value they see is pressuring other would-be competitors to also implement ActivityPub. I suspect they do genuinely want to grow the Fediverse… because doing so would increase the amount of data they could collect and sell from it.