By the look of it, poor push-back wallah's first (and very likely last) attempt at trying out anything bigger and more powerful than a three wheel scooter...
Yup, couldn't be any other reason. Blame the 'wallah', problem solved.
Oh wait...
More unconfirmed chat on the subject here at breakfast in JED this morning........
The engine went into full power during pushback and the tug got 'sucked' into the engine nacelle. The driver managed to jump clear.
How he wasn't then sucked into the engine was not discussed.
Ah!
Still, never let the truth (whatever it is) get in the way of a good story eh?