Not really. Do you know how many proprietary, company-specific extensions and modules there are of the Linux kernel out there?
Loads of companies choose not to contribute their stuff back upstream. I don’t know why the NSA did originally in the case of SELinux, but I would guess it had to do with transparency, national defense and not carrying the burden of a module / fork solo. They were also not the only contributors even early on, according to the Wikipedia page
Also, if I recall correctly, there was no other option for MAC back them (no AppArmor or Tomoyo).
No, he does not care at all. Nope. Doesn’t care about what the media says. No bearing, none.