surely the A330 would have its own A/C packs and therefore would have the A/C running in the ground?
For all we know, it could as well be a bleed problem, it's not because pilot shutdown engine and engineers working in the cowling that it is engine related. And some bleed problem do not permit use of ground cart as well...
The danger of trying to second guess the crew without ALL the information.
But agree, they should had tried to explain the situation to the pax, whatever it realy was.