Tldr of what I've posted elsewhere; I'm undecided at this stage but leaning towards defederating. When more information is available I'll make a post soliciting feedback, I don't want to make a change like this without user feedback.
You are doing all the hard work to run this instance, I for one, respect and support any decisions you have to make.
I would prefer to stay on an instance that is federated with Threads; The whole point of federation is to interact with other instances, regardless of who runs them, as long as they don’t push offensive content (spam, hate, worse).
If Threads does not behave in a respectful manner to smaller instances (and all instances are going to be smaller than Threads) they should be blocked.
Right now though, I support a “suck it and see” approach. If we (you, the server, other users) are not enjoying the experience with Threads, block them and walk away from them.
I hadn't thought of it, but one of the admins on the mastodon part of the fediverse made a good point: We might not have a choice, we might all have to defederate and blackhole threads because they could hit the entire fediverse with so much traffic it'll destroy our servers and our internet connections.
With the talk going around of creating a dynamic Blocklist to defederate instances infested with trolls/bots it wouldn't be to hard to create another one to block instances federated with Meta. This would fix the problem you mention.
Defederating with for-profit instances should go without saying. They are motivated to financially exploit communities like this, at the cost of the users.
Wouldn't it be worth waiting and seeing if they even decide to Federate in the first place before jumping to this kind of measure?
It seems premature to start pre-emptively blocking them if they were just building their own separate app network, rather than federating it with other Lemmy instances.