It's more like locking your door and barring it up really good and making it inconvenient for you to get in or out and makes your place less appealing to others, and at the same time you've got several wide open doors behind you.

Federating from threads accomplishes nothing. It's just echo chamber hysteria. Threads isn't even organized around communities, it's organized around people, by default no Threads users would be in Lemmy communities and we wouldn't see any of their content.