Oh, man, I still remember most of the problems that I/We had working on one of these back in 2012.
Neutral switch completes a circuit, so pulling connector off should not engage AutoPark.
I would strenuously advise you to pull the fuse for AutoPark, it was an option that had to be ordered with the chassis. Oddly, I remember the fuse being in the UpFitter fuse block.
I also remember that there was a lot of water ingress into the neutral switch back shell / connector. Upon reassembly, we filled the connector with silicone dielectric grease.
At the time, we were not disabling AutoPark, just trying to get the thing into gear. Neutral switch leaked a lot, likely from water ingress.