Indeed, probably for the best, even. You don't know what systems Claude will have changed in the code especially as these days people aren't even reading the code and Anthropic has a history of trying to sabotage others' code such as during the Fable release debacle where they outright said they'd do so if you're working on frontier AI for example. I wouldn't let any sort of company like that anywhere near critical systems.
The point is: using Claude to design a website, do accounting, run a marketing campaign, is not a supply chain risk for the DoD, but taken literally and given the scale of the DoD "no DoD supplier can use Claude for anything" clearly is punitive.