This is true. I think they're leaving quite a bit of info out of the post, though. I'm not certain where the information was obtained and how personnel didn't exactly know about it, but there are standards across the board for DoD, DoE and other Government agencies that their networks have to adhere to.
For specific sites such as Creech, they are under their own 'honor system' of cyber rules, but all traffic from each site is part of a government leased backbone (or fraction thereof) which is somewhat of a DoDNet connection. Like the DoE, it 'should' be keeping track with netflow analyzers and heavy packet logging/sniffing with a series of IPS/IDS devices at each site. Even the DoE does this with smaller sites (and by small, I mean 10-20 employees).
That said, they may have it monitoring as a SPAN, but probably only have notification and visibility from 50,000 feet in DC, where they really can't do anything about it because the DoD HQ only has access to their OWN ASAs, and not their internal network. Basically, they know where it's at, but can't get to it.
It's convoluted, but the communication part is where the issue comes in to play. I seriously can't see how this happens in such a horrible scale, considering all Federal requirements for network infrastructure. It's unacceptable.