I think you're OK pulling up the bike from the grab rail. The grab rail is screwed into the rear subframe which is made of the same material as the rest of the frame. I believe the frame is stong enough for this. I think it will take more leverage than just picking up the bike to bend it.
In fact, in the Aug '05 issue of Motorcyclist magazine Street Savvy article shows how to hoist the bike onto the sidestand to be able to spin easy 180s to get out of tight parking spots.
"... place your left hand on the left grip and look for a good handhold for your right hand on the bike's right rear side. A passenger footpeg bracket, right-rear passenger grabrail or a frame tailsection downtube are good spots for this."
Granted, this is distributing weight on more than just the rear subframe, but I'd be a bit scared of a frame that I couldn't lift the whole bike from. I'd even go as far as to bet you could hook that sub frame up to a come-along or winch and lift the whole freekin' bike!
Hey, space saver idea, hang the bike from the garage ceiling!