I have never seen a blown tire burn a bus. I have drug flat tires many miles more than once. I think this bus had a brake hang and drag, it turns the drum cherry red and the heat blows the tires. The tires then provide the fuel to burn the bus.
The emergency diaphram that causes this is difficult to diagnose as you will only hear air leak while close to the brake can with the brakes released. (That can be dangerous, the bus can roll).
If you are an experienced driver familiar with this problem, you will PDQ physically check both emergency diaphrams any time you have air loss from the rear tanks because that is the only warning you will get before the fire starts.
DD3s are designed to eleminate this problem, USDOT required DD3s on passenger busses for many years before someone lobbied to get spring brakes allowed. Guess its ok to burn one once in a while to keep costs down.