It means they release the model so you can run it yourself with enough hardware. Kind of like open source. Governments and large companies should be self-hosting this kind of stuff because of security, availability, and IP-leak risks anyway.
With LLMs, there is some risk of hidden malicious actions embedded in the weights that you can see until you ask it a magic question and it says "activate skynet."
Whether or not the government is doing this because of fears of hidden actions in the weights or just because OpenAI/Anthropic CEOs told the government to give them more money is unclear.