One of the quirks of tech transfer offices is that they have emerged from government agencies and universities because it turns out that making technology and patents freely available doesn't do much for commercial adoption.
It's not... you're probably thinking of the fact that anything NASA releases is not copyrightable. This doesn't imply, however, that they must release everything.
Anything sufficiently sensitive or representing a US advantage over other nations is ITAR controlled.
NSA, not NASA.
FYI: I was replying to this part of the comment: "Nasa does this to some degree..."