This isn't the government subsidizing a private venture, it's a private venture offering a discount to the government. What does profitability have to do with whether or not the government should purchase their services?
If GSA is already considering vendor lock-in as they establish new public services across multiple agencies, the natural move is to build them to eventually transition to a federally-owned and operated provider. Especially with how involved the U.S. government is in limiting capabilities Anthropic provides to consumers today.