That's a nice long thread. Lots of neat ideas there.
I do have a manual on order and had my dealer print out a diagram for me. The darn thing is so small that I need glasses and magnifying glass to see it. I hope the book has a bigger foldout or something. More importantly I hope the book talks about the logic. It looks like all wires go to the ECM which would mean everything is programmed. We talk about wires going from the switch to the front or rear but they really go from the switch to the ECM and then to the front or rear. If they programmed away the ability to do what so many here have done before I don't have many options left. I haven't been able to find a thread on this subject where one of the participates had a model like mine (2015 570 full size) to see what they did. Right now it looks to me like what worked even last year won't work anymore.
If it's like mine, you'll get an 11x17 folded drawing with really small, hard to trace lines on it and still need a magnifying glass! The schematic will show all the connections but doesn't talk about logic internal to the ECM. Just lines in and out of the box.
You are correct, it would be very easy for Polaris to add an extra bit of logic to the ECM to keep the rear locked when the Hilliard was energized.
I don't know really how to determine that for sure other than looking what you have already seen as I've never seen anything regarding the actual logic in the ECM's. If there are tuners like Power Commander, they may be able to manipulate things or confirm what you're looking at, although I'd probably try for a cheaper workaround...