Can you stay in your vehicle if ordered to exit? Granted, the police never stated he was being detained, and they never told him he was not.
Based on what I've tried to learn about these procedures, his next step should have been to information he officer that he did not agree with the delay and would like to continue on his way, in order for the officer to make a statement if he is detained or not.
From Attorney General Opinion 00-147
http://www.tn.gov/attorneygeneral/op/2000/op/op147.pdf
QUESTION
Whether an individual who intentionally but passively refuses to obey a law enforcement officer’s
reasonable, lawful command commits an offense under Tennessee law?
OPINION
No, an individual who intentionally but passively refuses to obey a law enforcement officer’s
reasonable, lawful command does not commit an offense under Tennessee law because force is a necessary
element of resisting arrest.
So unless he tried to drag you out of the car and you resisted you shouldn't be considered violating the law by simply not getting out because asked/told to.