Selling a pen labeled "this pen will refuse to sign certain orders" is not sabotage or malicious and is thus not a supply chain risk. The DoD is free to not buy from Anthropic, but designating them as a supply chain risk is incorrect, as well as arguably arbitrary and capricious given their public criticism of Anthropic's beliefs.
The DoD buys from suppliers, who buy from suppliers, and so on. Hence supply chain. Hence supply chain risk.