The Chinese resellers that are happily operating outside of the terms of service?

Or the reseller's customers, that are knowingly buying a potentially fake service?

Or Alibaba, also using resellers to break terms of service with the aim of attacking Anthropic's business?

INAL but I think Anthropic would be able to argue an "unclean hands defence" to prove they are not defrauding anyone:

https://en.wikipedia.org/wiki/Clean_hands_doctrine

In short, you can't knowingly break a contract and then complain that someone else is not treating you fairly with regard to that same contract.

That doesn’t necessarily mean much. You can put plenty of outrageous statements into any contract that automatically doesn’t make them binding.