I know OP has figured it out, but on my LS I can start it, leave it in neutral and get off, then start the PTO when I'm not in the seat. This is how I do it when I'm running my chipper.....
My old Kubota L6060 also had a Grammar air ride seat and it would not flip forward to allow pto use.my simple solution was to put my toolbox on the seat when I was chipping. It was a bit of a pain but it worked. I would not mess with the seat switch, I had a defective one and had to wait months to get one from my dealer through Grammar.