Not true - in general, the reason you can't push down car windows is because they're driven via a worm gear to increase the force exerted by the motor, but you can't back-drive a worm gear.
I was pointing out that it was interesting that in the car that was actually produced with this type of door, they used belts (instead of the worm gear you're talking about) so that the door could be manually opened.
This is probably the approach that any other mass-produced version of this door would take as well -- avoiding the worm gear so that the window & door could be manually moved if needed.
