a user choice in the GSX setup would be the best i think, because then the user can decide if this stupid question is comming up at every pushback.
As I've said, the question is not "stupid", regardless how many times you keep using that derogatory term. It has been asked by users, of course, and users are always right you know...
As I've already replied to you in another thread, assume your APU fails: that option would give you the chance to start the engines before pushback, without being left out in the cold with no way to start up.
And yes, we obviously know what would be the proper way to fix this: having the pushback crew wait for the engines to be started at the end of the pushback, and offering you to push you back in, to sort the problem. But again, it will require adding the ability for GSX to Pull (to go back to the parking), which will be added in the future pushback upgrade we'll release sometime next year.