If a person is open carrying in a state where it is legal, the police have no business stopping anyone, or asking any questions. They don’t have to like it, but it’s Constitutional, which they are bound to uphold.
Personally, I think it should be legal for “felons” to open carry too, after they have served their sentence.
You’re right. Open carry is legal. Just because someone is doing it is no reason to suspect they are breaking the law. If you think it is ok, then consider police that stop, detain you, point loaded weapons at you, handcuff you for 45 min or more merely for driving a car. Sure it is legal, but it might be stolen, you might not have insurance, etc. Etc. Let them fish for something for a while, just because you dared drive. Does that sound reasonable? Stopping open carriers like this is no more reasonable.