The DoD really dropped the ball by granting access to this information to such a wide group of people, according to the article. "Thousands of people". What happened to need-to-know?
The IC was raked across the coals for years over being overly secretive and is still blamed for 9/11 because they had the pieces, but wouldn't coordinate.
Balancing security and communication is very tough and the nation specifically choose communication.
That 1000s of people had access and didn't leak it speaks to the strength of the system. I'm sorry that one guy was eff'd in the head and felt he needed to buy friends with classical documents.
At the very least, access control systems should've flagged unusual access to more information that this person would've had a need to know. But as big as the US intelligence and defense apparatus is, not every agency, program, and office is gonna have rigorous enough controls to catch people like this. Seems like the lesson should've been learned after Manning and Snowden.
The USAF alone has something like 100,000 aircraft maintainers, all of whom have a need to access that data to varying degrees.
In my firsthand experience, having been a military officer with a security clearance, this rarely if ever happens. My point about the aircraft maintainers is that it's fairly common and in fact rather mundane that "thousands" of people do actually have a need to know.
It isn't, however, surprising. This is just another in a now long list of similar failures, increasing in frequency. Our intelligence and military leadership is not competent.