I thought the same thing about him not being set up right for the curve but in the picture about the middle of the curve it appeared he was ok. I think we are missing several frames from the middle of the curve till he was in the grass that might give us more to go on for what happened.
I saw one of these last year that showed a guy doing something similar and then hitting a vette. It was eye opening as well.
Just from experience watching the various bikes/bikers on the Dragon over the years, a lot of them see these photographers pop up along the route and become so focused on posing for the picture that they forget to control the bike and end up like this guy.
Not being right setting up for a curve is often the problem up there. I followed a kid on a new Sportster across one afternoon. He acted like he was afraid to lean it in and sure enough it bit him before it was over. He ditched it. I helped pick it up and made sure he was relatively ok. A lot of riders seem like they don't trust their tires enough to lean it over. Tires nowadays aren't like they were when I started. They'll stick long past where you think they'd give up.
They also want ease into the lean. I was that way when I started riding and have tended to do that when I first switch bikes. When you try to ease it, you start early and bike tracks to the inside before the peak of the curve. So, you've just made a 25 mph curve a 15 mph curve. If you're running 35, it's going to sling you out of the road at the top and there's nothing you can do about it.