alt Hacker NewsWindows is not public infrastructure. If the government's reliance on it has reached the level of "national importance", then that's the problem that needs to be addressed, not Windows' ownership.
Public infrastructure should be built on open-source, period.
Why is Windows not public infrastructure? Because it's privately owned, or because it's not relevant to enough of the public? I argue that it is public in function. My thinking matches yours as regards OSS.