Is it ok for the trunk bike rack to rest against the glass of a hatchback?
Being both a hatchback owner and a trunk rack owner, I can tell you yes...and no.

I've got a Saris Bones 3 rack and the feet have etched the window slightly. While the feet are of a more rubbery plastic, I think it's when there's dirt and grit underneath and moves (even unnoticeable movement) it grinds at the window. It usually cleans up pretty well, but I can tell where the feet marks are.

I would recommend putting a sock or other cloth over the feet (the body ones wouldn't hurt either). Also, make sure the contact point is clean, which means lossening or removing the rack to clean behind it.

Lastly, I've never had an issue with the rack slipping or moving, but most of the weight (even on your type of rack) will be going to the lower feet or bars.