I would imagine there is set of criteria which would absolutely trigger the fighters to bring down the plane, but those were not met, and those in charge erred

I would imagine there is set of criteria which would absolutely trigger the fighters to bring down the plane, but those were not met, and those in charge erred on the side of caution. Bringing it down aggressively would not be without its own risks, as the aircraft and debris are still going to crash down somewhere. Additionally it means taking the life of a citizen, and causing a lot of damage that the National Guard is then somewhat responsible for, and potential PR backlash. I believe it was clear early on in this case that the guy was not a terrorist, and he didn't intend to hurt anyone, so adopting a "wait and see" approach seems quite smart.