I got a number of answers that sound very weak to me, and basically point to a "fail" of the fediverse in its own nature if threads joins. Kind of disappointing.
To me, the key idea of the fediverse is that it's federated and should work as a whole, no matter who joins. Most of the answers below support the opposite. They are basically saying that the fediverse should stay within the "fediverse", which is exactly what non-federated social media are doing. Meh.
They probably want to monetize on podcasts too, in the same way they do on videos and music. At the moment, Google Podcast is completely free and ad-free.
I came here to say exactly this. IG and all the others are private companies, with their own terms and conditions one agrees on, and also agrees those terms can be changed by them at any time. Moderation of content is part of it. Deal with it, or don't use them at all.
Well at least he did not lie then!