I think you have this pegged. Not every despicable, cowardly act is the work of Islamic terrorists.
I’m guessing it’s just a whackjob who went off the deep end. What pushed him over, and if he had anybody else cheering him on, who knows. I’m sure there are people trying to find out, and I’m sure that political hay will be made, no matter what is found out.
As a veteran, it pains me to read reports that the perp was was a veteran, but then again, so was Hitler.
And Lee Harvey Oswald. And Hollywood anti-American "action" movies most always show nutcases as former military.