To all the people wondering about metas intentions in this it's not the big bad corporation taking down the upstart competition. All the people saying it's EEE can't show any sign metas doing this or even wants to because the strategy doesn't work, any time a company does it it either doesn't take off or they get brought up on anti-trust laws. Show me a standard that was destroyed by EEE and I'll show you a standard that never took off in the first place. All the usual examples given, email, java, html, remain open standards to this day.
The truth is the fediverse isn't competition to meta, it's a fraction of the size and is populated by users who would never use meta services in the first place. They can pretend it's a competitor though. If twitter does actually collapse and people switch to threads meta will face anti-trust suits for owning the three largest social media platforms. If they add activity pub support though they can point to the fediverse and say it's competition, even if it's only 1 % of the platform. They also have to deal with EU interoperability laws that might start getting enforced.
TL;DR this is about compliance for meta, not conquest.