Though I think that he was reckless and should have protected himself, he has proved that you don't need to shoot a bear on sight for protection. There are many ways to discorage attack, including using a soft cooing voice, they don't know what he is saying just the tone is enough. I have seen his films and I consider him an expert of sorts. I actually liked watching him play with the foxes more than the bears. But it was foolish not to bring a gun, just in case. He may have used politics for an excuse, but I think that when you get right down to it he was once again addicted, but this time to the adrenaline rush of being so close to death.
Maybe the bears were just hungry and didn't care at the moment what their dinner sounded like.
From the article--
Most of their food was found in bear-proof containers near the camp.
If his soft cooing did not work, he could have climbed into a bear-proof container.