Sorry GM, lost sale.
That's maybe a little dramatic at this point.
I agree GM has supplied a crappy seat, I think they will revise them, but if you can't wait, fixing the seat takes 15 minutes and a few bucks in materials. If you can't do it yourself any upholstery shop can if you print out the thread. Don't let them charge you a thousand, it's an EASY and cheap fix to get the seat however you like it.
If you like the car, get it, and tune it to your liking. I'm very happy now, happier than if I bought any other car. You can be too.