Not sure about ethics, but if the argument of "excessive moderation overhead" still holds true for staying defederated from Lemmy.world, the same should apply a thousandfold for Threads.
Oh, that's nice. Realistically, LW probably has the most chances of weathering a massive user onslaught, they kind of had to do it already, so hopefully could extend the same actuation protocols.
From what I understand from the video, Threads is also going to do it in several phases, starting with allowing the fediverse to follow a select few people on Threads, then allowing more people to get followed, then bidirectional messaging, then following anyone from anywhere.
They're also pairing it with Threads launch in Europe, then citing it as a reason along "compliance" and "scrutiny on our company", which IMHO is the main reason they're doing any of this at all, since the EU seems to want open communication protocols and crack down on these international social behemots. The stepped approach means people on the fediverse will first be able to follow people on Threads, before the reverse happens, so content creators and influencers (or politicians) will want to use a Threads account to have a larger reach... which is how Meta might try to lure people off Mastodon, but we'll see.