The ban is 100% politically motivated retribution because Anthropic told Trump and Hegseth to go pound sand. The US government is purposefully screwing with the company because they refused to play ball and embarrassed the administration. It's a transparent effort to take revenge on a perceived political enemy as well as promote a jingoistic agenda of "US Citizens Only" nationalism.

That's easy enough to believe, but the truth seems to be a bit more nuanced.

In the end, the actions of the administration have doomed the US to lose any lead to the Chinese.

100% this it's the usual transparent Trump revenge tactics. The sad/scary fact is that there seem to be plenty of people who either can't or choose not to see it.