As far as the front desk was aware of, it counts as a stay and qualifies for the 10k bonus. In fact, they were going to try to have the resort credit qualify as well so $1500 worth of points isn't bad at all (they figured some would have spent that anyways even without the credit).
As for how much the resort credit will cost the hotel, it really depends on what you're going to use it for. If you go to the spa and pick up $1500 worth of skincare products...I highly doubt that the hotel is getting it for 25 cents on the dollar. If you spend it all at the restaurant then its not costing them much...
But bottom line...great job from Hyatt mgmt at this property going above and beyond to make everyone happy. Not a single complaint about being 'downgraded' and alot of first timers at a Hyatt property were rushing to sign up for GP.