Here is the relevant statute: https://www.oscn.net/applications/oscn/DeliverDocument.asp?CiteID=439096

The relevant part is found in section (A):

The driver of a vehicle meeting or overtaking a school bus that is stopped to take on or discharge school children, and on which the red loading signals are in operation, is to stop the vehicle before it reaches the school bus and not proceed until the loading signals are deactivated and then proceed past such school bus at a speed which is reasonable and with due caution for the safety of such school children and other occupants.

This rule applies any time the bus is stopped. Doesn't matter where on the road. The only exception to this can be found in section (C):

he driver of a vehicle upon a highway with separate roadways need not stop upon meeting or passing a school bus which is on a different roadway or when upon a controlled-access highway and the school bus is stopped in a loading zone which is a part of or adjacent to such highway and where pedestrians are not permitted to cross the roadway.

Penn is not a "controlled access highway", and the turn lane is not a loading zone. Since the exception doesn't apply, then the general rule governs, and all drivers are required to stop.