Lee01 didn't develop that circuit, I did. In or around 2007, I read a post at another forum about a problem with the power windows. I took inspiration from that post and develop a schematic on an excel document. What Lee01 did was to take my schematic and put it on another format to make it easier to read. To say he developed the circuit with many others is just plain dishonest.
I decided to keep the original relay because I like to maintain as much of the originality of the system as possible. You could remove the relay with no problem...but as GrandAm said, it would work with or without the key on. The original system worked only with the key on...which can be irritating so I see why he changed it. The relay grounds to the steering column via the fastener.
I also had a redundant ground from the motor fasteners to somewhere suitable in the cabin. I've since rethought that after seeing what 4speed did. He simply grounded the door rather than try to run a ground from the power window motor. That make more sense to me.
Well, I developed that circuit years ago and creative people need to do new things. I've since developed a step by step process for adding an AUX port to the Delco AM/FM cassettes, 8-tracks, and AM/FM stereo's from 1978 through 1987. Although it's a cable mount solution, I do have parts ordered that may solve the mechanical issue of installing a port on the bezel itself. But the electrical is sorted out and it works. And, it doesn't permanently destroy or alter any part of the radio. That process is documented on another trans am forum.