Maybe I’m just being naive, but this seems like an argument in favor of federating with Threads. One of the reasons Facebook and Instagram are so effective at driving engagement is that users have basically no ability to curate, sort, or filter the content that they see, especially since third-party clients are banned. You can’t even view most things without logging in.
The implementation of ActivityPub in Threads is a strange departure in this context - (federated) Mastodon users can view all of the content Threads has to offer without subjecting themselves to Meta’s arguably predatory curation algorithms. It almost seems like an escape for people who want to use a Meta-sized platform without Meta getting its grubby little fingers all over your mental wellbeing.
If people are worried that Threads will affect likes and comments (and therefore like/comment-based sorting algorithms) on other instances, it should always be possible to exclude Threads’s contribution to those metrics, no?