if you will read case law, you will see that even after a stop predicated on the basis of the registered owner having a suspended license that once it is obvious the driver is not the registered owner, reasonable suspicion is no longer present and the detention now becomes unlawful unless there is other justification to continue it. How far the involved cop can go is in question in many jurisdictions.
It goes much further than the simple justification of not being able to see the driver prior to stopping.
The kansas v Glover case I linked earlier takes it even further and questions whether it is even reasonable to assume the registered owner is actually driving the vehicle. Apparently even the Supremes have an issue with jumping to conclusions too quickly and appear to be considering the point that the owners license being suspended doesn’t justify pulling over an unknown person. In essence the current situation allows for a stop not based on any actual evidence leading to suspicion of a crime but extending the registered owners issues on to the vehicles which is allowing a person who the police have no reasonable suspicion to stop be stopped. While I suspect Glover will lose given the broad definition of what is reasonable suspicion in the current political atmosphere, the fact they have taken up the case at all should give a person pause when suggesting it is as simple as associating the owner with the vehicle and that suggests there is a crime being committed.