I can understand your discomfort and I'm not trying to be rude but I have a few questions.

How do you know there's a camera on the thing and how do you know what the goggles do?

There could be several other things he's doing. As an engineer at the airport maybe he's running some kind of simulation, maybe it's a new kind of super nerd video game and the goggles are the "screen", maybe he's testing a prototype of said super nerd video game and he will someday be a millionare.

I just don't see someone trying to be a peeping tom all out in the open like that. And I bet he'd tell you all about it if you said "Hey, whatcha doin?" the next time he's out there, I'm sure he'll geek out all over the place to tell you about it.