Meta Permits Its A.I. Models to Be Used for U.S. Military Purposes

Can a company prevent the government from using its technology? I thought the government could already seize/utilize/reverse engineer anything they so deemed fit.

Yes, and it's the same with FOSS software.

Facebook already made a statement sayings it's against their terms of use.

There is not much you can do if the morally corrupt use something that is out in the public, specially if it is out in the wild west of license enforcement.

Most of this more open licensing depends on people being honest. If someone lies, cheats, steals and kills people for a living, it would expected for them to take someone else's work and use it against the terms of use. They probably just say the obligation as it does not count in their country.

There is a difference between allowing use and supporting a use case. Supporting would be, for example, adding military specific training to the model. If we were talking about a car or a tractor nobody would bat an eye. Should companies not sell potatoes to the military? To be clear, I am not a fan of developing for the military, but the idea that a TOS will stop AI being weaponized is a bit naive. Similarly, if the goal is to responsibly introduce AI to the world then shaping the military's adoption of it by allowing its use, without specifically supporting it, is probably a good path.