That isn't really how contracts work, NASA is paying Lockheed to do the work and certify its good to go. Unless there is some meeting where Lockheed engineers were saying "the pee gonna freeze" and NASA said nope we have to go we don't have time to fix it (sort of what happened with Challenger), its up to Lockheed to deliver what they were paid to. In this case a working human spaceflight certified capsule.

It seems plausible to me that a noncritical system like this wouldn't be specifically called out in the certification of the capsule, we have only made a few like this before, and the worry is more "will this blow up and if something goes wrong can we fix it" not "is the pee tube warm".

I do think NASA should be more involved in the engineering of these things, but the rich want to mine asteroids or whatever, so they lobby for private spaceflight and that's what we've got now. Thus the corporations get the blame when they screw up, not NASA.

I'll correct you there. NASA can only check what they are allowed to. Lockheed will not share shit. One big misconception is that NASA has access to all proprietary info. These sleazy contractors do every single thing they can to hide as much as possible, and the back room golf course deals enable it. Additionally, nowadays, if NASA disagrees, they can basically say fuck off and do it anyways. Contractors have fucked NASA for decades now.