Yeah, sounds weird at first, but the motor is stalled by being "flooded" with fuel.
That applies to gas engines maybe. Gas engines require an air/fuel mixture of 1:23.5 to 1:24.5 to ignite. Diesels dont, you can put in as much fuel as you like, and it will run as long as it doesnt hydrolock...
"Stuff a coat in the air cleaner" is no longer the cure all for a run away motor - and quite frankly I doubt that it ever really was (-:
Last time i had my propane powered car for a DMV test it was: the inspector stalled the engine by putting his hand in front of the air cleaner suction tube. That stalled the engine within 3 seconds, he did this to check if the electric solenoid valve on the propane tank would cut off the gas flow immediately after the engine stopped, which is mandatory for safety.
I had a colleague who worked at a crane company, and they had a crane with a Mercedes V8 diesel that didnt shut off due to a broken shut-off solenoid. He tried to stall it by pulling all 4 hydraulic crane levers at once. The effect was that the engine kicked back and began running in reverse: The pumps also turned backwards, pumping the oil back into the tank and sucking air, so it wasnt possible to stall it again. Or at least, have it kick back into forward motion.
Anyways, before he could grab tools to open the hood and rip off a fuel line, the engine had already damaged its crankshaft bearings because the lube oil pump also ran in reverse, draining all the oil from the bearings.
Lesson to learn: Even experienced mechanics can create a lot of collateral damage by unforeseen events...
And with that automatic transmission, there is no way you could have stalled it, the transmission oil would have boiled out before the engine went and both would be toasted...
I hope your boss has additional insurance that covers this.