in this case we don’t talk about users who want to block users of another instance. The problem is not the users of meta. The problem is meta itself and all the problems it will bring to the federated network. Whoever cannot see that their intentions are not to promote federated networks but to exploit and extinguish them, is just naive.
meta (threads) will not support fediverse already. They said they will do in some later version. So for the completely practical part, you don’t need to do anything right now.