I've also worked for a defense contractor, and the company I worked for, and the facility I worked at, took securing classified information very seriously. The consequences for screwing it up can literally be prison time, so I'm really surprised to hear the company you worked for didn't take it more seriously.

In this specific case, it doesn't sound like the "sensitive Pentagon Files" were classified at all, though, so it's probably not as big of a deal as the article is making it out to be.