If they didn't why would they develop tools to federate? It's obvious that the threads project was sped up significantly following musk's obliteration of Twitter, so they wouldn't go out of their way to implement such a feature if they didn't have a very specific reason for it.

A company's goal is maximization of profit, so don't assume they intend anything else. The activitypub userbase is too small to be a significant addition to their userbase but in this way they can destroy it before it escapes their control. They don't take risks. Mastodon could seriously compete with threads and it's gaining popularity. If one more big boom happens it might be too late to stop the fediverse from competing with meta in the most cost efficient way possible. Do not be lured in by the false sense of security, meta wants us to help maximize their profit. We aren't doing that right now so Meta wants to stop us (or limit us, whatever they deem more profitable)

I bet XMPP users were saying the same thing about google talk, maybe try reading the article?

Might be because of Threads, and Meta seeking to use ActivityPub themselves.

I don't disagree with you though; I don't think the fedi is big enough at the moment to register as more than a blip on their radar, as you said.