If someone uses a TSU to hold a suite for days/ weeks/months in advance of a stay thus making I'm the suite unavailable for the hotel to sell or for other customers to book, then cancels the TSU last minute because reservation holder sees standard suites are still available and thus will most likely get upgraded to a suite upon arrival, that is abuse.

I would hope Hyatt can track people who do this and ban them. It ruins it for Hyatt, property owner and other guests.