by adding features you can only get if you are on their platform. Their goal is to make most people prefer the Meta version of the fediverse
Why is this a bad thing? This is the system working as intended: a company forced to make a service people want, rather than just taking users for granted. You resist enshittification because you’re not being held hostage through access to content, so the company is forced to make the service good. And this will attract other companies to produce competing services.
And besides, most people already prefer the Meta version… they already have the user advantage. There’s already way more users locked in their services than there is on the rest of the Fediverse.
Assuming you mean “Can Mastodon instances defederate with Threads?”: Yes. Mastodon (and similar services) run on the ActivityPub protocol, which allows them to decide who they do and do not federate with. Many instances have chosen to preemptively block Threads, many have chosen not to. Pick what works for you.