The tailwheel looked like a mechanical extension, not a broken mechanism, overcome by inertia. So is it possible that Leeward was configuring? His roll left at the beginning was controlled with right aileron, and the intitial climb seemed an input/climb. His later roll left (prior impact) mimicked a pylon hug, (there seemed to be some 'pull'); so had he started to regain consciousness?
Depending on the proximity of the high octane to the cooling Water/Methanol mix, the vaporisation rate may have blended the volatile fuel with water, creating a non explosive, non flammable (transient) mixture. High Octane Fuel burns more slowly than lower Octane, but I doubt that had too much to do with it. I guess about 40 gallons of fuel left, the size of an SUV fuel tank, so on its own, one would expect a fire, if only a brief (flash) one. Are we sure there was no 'brief' combustion?