how are you going to moderate millions of users many of them huge influencers with fans who follow orders of attacking whoever they're pointed at when they come for your users mastodon dot social?
you're going to have to do Threads' moderation for them because its your users they're going to be attacking, harrassing, threatening and sending abuse at.
if you federate with threads you better be ready to have enough moderaters to handle however many millions of users they have.