Private industry could easily profitably operate it, however the core technology - the atomic cloc - is nuclear weapon grade technology, which is simply unavailable to anyone but the government.
I’m sure HP/Agilent/others will gladly sell you the newer state of the art modes as well (although as high precision, very low volume devices they’ll be fabulously expensive); if an industry consortium wants even more precision you could staff a research team and shave off a bit more frequency error.
However, I think for industry it’s cheaper to use GPS receivers instead of supporting a powerful transmitter (and its use of value able spectrum). GPS can keep incredibly accurate time.
Sure, as long as the satellites are up and you have line of sight.
Aside from hostile actors, space debris, solar storms and other threats exist. We shouldn't take for granted that our satellites are just always going to be there.
https://io9.gizmodo.com/what-would-happen-if-all-our-satelli...