Would it be possible he was just used without knowing it himself? Maybe he rented the cybertruck and was going to Las Vegas for a holiday or something, got ambushed at some point, murdered and the stuff piled into the car, then the car drove to the point and the load was remotely detonated?

Maybe he got chosen by an accident, was in the wrong place at the wrong time, or maybe he was chosen way earlier by the same people who radicalized the New Orleans type, lured to Vegas somehow by them because he was deemed suitable for some reason as the scapegoat, and fell for their deception. whatever it was (you won the lottery, all expenses paid vacation in Las Vegas!!!).

Or maybe he was one of several soldiers that had been spied on and tracked, and happened to be the unlucky one who could be used due to something he did on his own, or because he fell for some kind of deception. Maybe there is some terrorist cell of more advanced operators who used both him and that New Orleans guy, the latter who they managed to radicalize enough that he did his part voluntarily.

Okay, it sounds rather unlikely and way more like a movie plot, but even that kind of more complicated stuff does happen in real life from time to time, however rare it might be.