Likely possibility: Messages from the Deep State cabal, whose agents convinced him to shoot up an airport as part of the Deep State's ongoing war on normals, with the goal of gun confiscation.
The terror groups instruct these operatives to put on the crazy act once caught.
At least going back to Operation Paperclip, nefarious mind-control projects have been operating under the auspices of our nation’s military and intelligence agencies. I suspect a significant portion of mass killings are connected with this and show up as mere cases of mental illness.
Of course, the moral decline of society is a recipe for creating dysfunctional individuals capable of mass murder as well. This is true even more so for individuals who have grown up in abusive situations.
Our society is operating under the weight of a large percentage (I would guess this to be more than 10%) of the population being severely traumatized and psychologically destroyed by childhood trauma, whether inflected unintentionally or intentionally as part of a mind-control agenda.
This is a recipe for societal collapse. And that seems to be where we’re headed.
That's proof he's nuts. :-)