The Verge article is paywalled for me, but the screencaps Alex shared in his toot don't really support his summary. The article mentions that Threads can import content from Mastodon as an example of the sorts of things ActivityPub supports, and that's about as close as it gets.
And then there's this:
The company is planning to create a roundtable for administrators of other servers and developers to share best practices and work through problems that will inevitably arise, like Meta's server traffic putting strain on other, smaller servers.
Emphasis mine. How would Meta's server put strain on other, smaller servers if it's not federating with them?
I'm fully willing to believe Meta wants to EEE ActivityPub, but this particular claim doesn't seem to check out.