I prefer not having loaded guns pointed to the ground and swinging up when my dog is out in front. IMHO, lifting the forend to bring the barrels up into battery provides better muzzle control.
The thought is that the act of closing the gun is the time when an accidental discharge is most likely to occur. Once the gun is closed it is easy to point the gun in a safe direction while bringing up the muzzle. If you are unable to bring a gun from pointing at the ground to a ready position without the muzzles sweeping something you don't want to shoot you keep them pointed at the ground.
BTW, how does a gunner lift the buttstock up and ease the lever over at the same time? Photos I've seen of the "butt up" method show the gunner's hand at the butt end.
That's correct, you can't do both. I'm of the belief that gun makers designed bolts to close under their own power.