alt Hacker Newsit may be really good pr, but it's really bad for their IPO. If their market for future models is usa only, their potential revenue is cut by 50% at least. (and it's even worse because it means Europe, India, and China will all have companies making their own models that anthropic needs to stay ahead of)
Another sibling thread already called this out, but mentioning here: it's not "USA only", it's "US citizens only" (and I'm not entirely sure how dual-citizenship interacts with this, but I assume you can't sell to them, either, since they are by definition also foreign nationals). A private company only being able to do business with folks they can verify are solely US citizens (who themselves are also willing to submit verification of said citizenship to a private company), has a relatively small pool of potential users.
And so if this policy holds, Anthropic has functionally had Fable killed by government intervention, and in a logically consistent world, this would imply all other US-based AI labs may also never exceed existing (read: Opus) capabilities.
What interesting times we live in, indeed.