Would appreciate the law, or company rules, behind this situation.

Passenger with no checked luggage is on a demestic flight AAA-BBB connecting to BBB-CCC. AAA-BBB flight is diverted to CCC due to weather and remains on the ground for 90 minutes, but not at a gate (aircraft is an EMB-170).

Passsenger is not permitted to leave the aircraft which makes sense if the aircraft is not at a gate. However, if the aircraft had proceeded to a gate could the passenger have been permitted to leave? And if so, could there have been any rules which would not permit reaching a gate?

Thanks!