I have never bled power brakes with the engine running nor have I ever seen someone else bleed power brakes with the engine running. That's just me. Don't see why the engine would need to be running just to make vacuum for the power booster when all you are doing is pushing fluid mechanically through the system and not trying to stop a three or four thousand pound vehicle?

BTW I was always taught that no question is dumb and not, I'll also say, be embarrassing. I think this was a good question