Which A/c was it, Q400? If so they have there own power unit. I cant remember or have seen the Dash 300 do a CDG flight.
Even so, once the engines are running, they then supply the power anyway to the a/c not the apu. So the above comment seems a bit strange.
Q400 does have an APU, true, but it would appear from the comments in the article that the a/c was on ground power during the turnaround. If the GPU drops off line, or gets disconnected inadvertantly, then the batteries take a major hit and it can take anything up to 50 minutes with engines running to reach the acceptable limitations for take off.
As for the ex-Rasher captain, frustration we can understand, but that is just unprofessional and makes him sound like a tool. Probably one of the guys who is leaving, so hopefully good riddance.