Anthropic and the Government both signed a contract. Anthropic is still abiding the terms of that contract. The Government is demanding that they be able to disobey the contract.
Implementation details TBH. They want “their boys” to do as said. No respect to agreement or legality as we can see in other dealings. They hold all they cards.
Everything is negotiable, and the Negotiator in Chief clearly likes to pull all the levers he can find, legal or not. (Well, the Supreme Court ruled that it's all legal if he does it, right?)