NSA uses tor, of course, and it's no threat to them that they run a lot of the nodes behind fronts.
NSA would use darkweb businesses as cover, and probably some of them are heavily infiltrated, you surely know the story of SR.
Time sensitive is not so much the big deal, low latency is not that bad really, what sucks about Tor is the time one can be waiting for a ping before it and the app protocol time out. On SSH it's extremely difficult to work with it, even using MOSH.
Other than that, I illustrate it in the Indranet whitepaper here:
It's not scaling. Per node bandwidth is moving up but number of nodes is not. It's been static for over a decade. The security and stability of the system cannot be in a positive trajectory in these conditions.