There's this stuff called evidence; it takes some of it to arrest somebody, and it takes a lot of it to convict somebody.   It also takes evidence to fire a State Trooper, and, unlike you, I suspect, I've actually been a part of doing that.   There is no way that you can know from this story what was actually going on in this event other than the driver apparently wasn't properly licensed and was cited for that.   How the driver came to be driving and what if any involvement in the bus being removed from its place of storage he or any of the passengers might have had isn't known to us, nor at the time to the Trooper.   But, go ahead and "summarily" fire the Trooper; he'll enjoy the paid vacation.