Sadly, not only does GC use UPS (not quite as easy as Fedex), it sounds from what was said above that they even specifically restrict changes or reroutes on their orders.
That plus not requesting a signature...recipe for disaster.
I've run into the problem with "restrictions" once before and it can be overridden through customer service. You just have to talk to someone on the phone if the service is unavailable in the My Choice UPS options...a bit of a hassle, but it's still doable. I agree with the signature required part...should be mandatory for these kind of things.