I saw the documentary. It's been a while. If I recall correctly, he was there to videotape people who were breaking the laws against harassment of the bears, etc, and trying to get the Park service to enforce their own regulations about it? (I seem to remember something about contractors bringing in tourists and breaking the laws as it was a preserve of some sort)
Whenever you hear people talking about the guy, you almost never hear that, as one of the earlier posters said, it wasn't "his" bears (I hate that term)...it wasn't the regular population of bears he'd gotten to know and be able to 'read' and who had gotten used to him over the years he was there...who killed him. The bears he watched had gone into hibernation and other, strange, bears had come into the territory. One of those killed him and his girlfriend.
I'm an environmental anthropologist and I hang around with a *lot* of biologist/researchers. Living for months at a time out in the wilderness is something that some of them do. There are risks, but it's not a death sentence to spend time around big carnivores if you know what you're doing and you're careful. The man *did* anthropomorphise the animals to a huge extent, but a lot of the really dangerous-looking stuff he did, was after he'd been out in the field a long time, had learned to read the bears, and they were used to him. It was still dangerous and foolish but not as bad as it looked. He didn't just get off the plane and run up to hug the bears.
He was kind of a nutjob but he wasn't as big a nutjob as he's often portrayed.