If the driver couldn't produce a rental agreement with him listed as a permissible driver, would that constitute a "reasonable suspicion" that the car was stolen?
I'm not sure I buy into the "It wasn't reported stolen" argument. If the driver had carjacked the vehicle and stuffed the body of the owner in the trunk, there wouldn't be a stolen vehicle report in that case either.
A call to the rental firm would probably ascertain who the driver is supposed to be.
LE had a suspicion....that SHE was possibly in trouble....or whatever. For all we know, the driver had a knife by his side.
Did he have cause....I believe so.