With a Hyatt week, you either use it or you get points to spend. Therefore if you needed to cancel, your “currency” upon cancellation would be X number of points. Feb 7 at Sunset Harbor is a diamond week, worth 2200 points for a 2BR (if that’s what you’d be renting).
If you cancelled prior to 60 days ahead (Ie ~Dec 6, but you'd have to count backwards for the exact date) of the reservation, you’d have 2200 pts to spend in the Hyatt system. But those points would only be useful really until the date of the owner week ie Feb 7 (during this time they would be quite useful, you could book anything in the Hyatt system- well anything you have enough points for). Once you get past the date of the owned week, the points move into “Limited Club Use”. Limited club use points expire in 6 months (in this case around Aug 7, 2021) but they are only good for reservations made within 60 days of the reservations start date. So LCU points are very restricted in their use and you don’t want to go there if you can avoid it. Additionally, once the unit is converted to points, they’d be in the owners Hyatt Residence Club account. It doesn’t sound like this owner would have any understanding of how to search and book on the HRC site, not even knowing they have points associated with their unit (Which is one of the most basic facts of Hyatt ownership).
The deposit deadline for those points into II is 4 months ahead of the check in date Of the owner week. So in this case around Oct 6, 2021. If you cancel before then, the points can be deposited into II and they are good for 3 years. They are quite useful in II, units are “cheaper” so you could possible get 2 two BR exhanges out of the points (there is a separate II points chart which you’d refer to; be aware you CANNOT book Hyatt units via II and there is no “Hyatt preference” in II as most Marriott and Vistana owners assume there is). BUT all II owners have an corporate account, so the points would go into the owner’s account not yours. Obviously you could have them book for you. But if they didn’t even know they had points, they are kind of clueless about exchanging so this would probably be an awkward way to try to use the points.
So, bottom line: you’d have trouble using these points if you needed to cancel the week, unless you did so fairly early (before Oct 7 if your desire is to deposit in II, or before Dec 7 if you wanted to use them in HRC). And to book you’d have to work with someone who doesn’t really understand what they own, so that would be a problem too. Not a lot of great options.