The article says that one of their employees sat next to a dude working on TESV on a plane.
The article states he sat BEHIND the dude working on TESV, i.e. a row back.
I'm really having a hard time believing that a guy who has signed an NDA will just suddenly reveal all the secrets of TES to a random guy on a plane. Doesn't sound very credible.
You're misunderstanding what happened. A journalist was in the row behind a guy who was working on TESV, who, perhaps rather carelessly, was talking on the phone with someone else about the game. The journalist caught on to what he was hearing, and, realizing he had the story of the month sitting in his hands, immediately started writing stuff down.
To me, that's very credible. You'd be surprised how safe people think they are with information in public places, especially airports. If you listen a little bit next time you're in an airport, you'll hear people talking about all sorts of things, because nobody thinks that anybody is paying attention to them. You feel safe in a crowd, so you divulge information you would never talk about if you thought people were listening. Hell, I had a friend once who was sitting in an airport lobby and the dude in the row behind him was a Lockheed Martin employee talking about an important government contract! People really do just feel safe with information in public places that are as crowded, busy, and noisy as an airport or an airplane proper.
So the idea that a TESV employee was talking about the game doesn't surprise me. All you need is somebody to understand what he's talking about (which wouldn't be too difficult if he was dropping phrases like "The Blades" all over), and bam, you've got your story.