agreed. actually at my new job theres' a guy that was a master gm tech. he said the same. so...he's working on the schematic, we couldnt print at work, so he's gonna bring it from home tomorrow hopefully. i'll post a pic and you can do whatever you want. grounding the wire will make the car assume the door is always closed (so yes, the lights wont come on, the door ajar warning wont operate, and the issue you have with the radio will be gone), but also, you're voiding warranty to any issues that may arise with the BCM, door, door lock module, and the wiring harness.
so make sure it's really worth it to you.
if it were me, i'd keep a little pocket screwdriver in the door pocket and just 'close' the door with the driver by puttin the tip in and sliding it all the way in (yes, pervs, that's for you), 'closing' the door with it open. i did it on BMW every time i programmed.