Big facility for keeping the worst of the sex offenders who served their sentences but are too dangerous to release "yet": HBM060: The Predators of McNeil Island | Here Be Monsters
But the guy still flew over populated areas. Seatac airport is surrounded by homes, this whole part of the country is pretty dense with houses, business, roads, you name it. He didn't have a pilot's license, he could have just as easily crashed upon takeoff into the many working-class homes in that part of town.
It seems like if someone really wants to kill themselves, there are plenty of ways to do it that don't put others at risk. This guy did.
True. But he seemed intent not to and he clearly wasn't thinking rationally. He said he didn't want to land at the airport because he might screw things up. His barrel roll was over water. And he did head over water when asked to, so as not to hurt anyone.
He was reckless and it was very dangerous. But he was suicidal and not thinking clearly. I feel very sorry for him and everyone who loved him.
On another topic everyone should note how absolutely calm the air traffic controller and pilot were when talking to this guy. This is how they're trained. Unbelievable. They can truly handle anything.