Here's my take....N/S traffic is controlled by the school bus lights. The N/S traffic facing the bus can still legalling turn left or right after complying with the stop sign. E/W traffic is unaffected by the bus, unless they turn towards the bus which they should stop. But flip the coin (for E/W turning) it is not reasonable as the bus is so close to see a red/lights from a 90 degree, even as one turns the stop arm (due to position, size of hood on bus) probably isn't visible until "bam" as you come around the nose of the bus, now that the vehicle is in motion even at that slow speed would be very hard to stop.
Best is to have the bus make the stop at the hydro pole (one back) from the intersection, now the bus has complete control over N/S traffic and any car turns has ample time to see the flashing lights.
