I don't plan on staying here if you defederate with Threads, but I respect your right to do it. The move seems unnecessarily reactionary and premature. I think the open web has more to gain from encouraging companies to invest in ActivityPub than it does siloing itself off from anyone who represents real growth in the space.
If you want the community to remain small, fair enough. I believe in a world in which every social media service is using ActivityPub; I don't care what or who they are. I don't even really understand what the anti-EEE crowd is afraid of? The protocol is run by a neutral party (W3C), I can't imagine any features that would compel major change, nobody that's already on the Fediverse is going to leave, you can always decide later to defederate... The system already seems pretty well protected against hostile action.