I would not fault the hotel much, unlike most of the responses here.
Clearly this is a Hyatt glitch. Hotel knows its inventory. But it is not reflected in Hyatt system. OP booked the room through Hyatt call center, not directly through the hotel, at later than 8:PM the same night of stay. Hotel would not have known the new booking. Hotel controls the room inventory, not Hyatt.
I have had instances where hotels called or contacted me to inform that they could not accommodate my bookings because of various reasons:
1. Age of minor of the property, like caldera cliff
2. Government restriction and closure
Not very common, but not huge deal. I worked with Hyatt to resolve the issues and most often Hyatt will give something like 10,000 points. One time I received the cash reimbursement booking at another substitute property.
So I would not make this a huge deal of "the hotel walked a Hyatt Globalist". The hotel would have walked anyone, regardless Hyatt status. This was never on purpose and intentional. It was Hyatt's fault, not hotel's.
Hyatt knew it is its own system glitch. This is the reason they offered the compensation. 20,000 points for a 5,000 point room, at 11:30PM? I think Hyatt handled it well.
Glitch like this happens. Mistake happens too. I guess as Hyatt Globalist, we all expect much more.
There will be more Globalists next year.