I only see two ways to stop this spam.
1) filter to see only posts from people in your trust graph
2) impose a real cost to post to all
Anything I’m missing?
Bottom line is that new users will be initially treated like spammers.
This attack is probably just a warm up. I would expect that we’ll soon see AI posts that you can’t pattern match, and overwhelming spam against both replies and DMs. I would expect them to initially target the folks with the largest follower count, then attacking new users.