I extend the invitation to friends but I have them prepay for the reservation. Yes, it is a hassle when cancellations come up and having to help them find a replacement reservation, but I'm not out any money or stuck using restricted points. My friends genuinely appreciate the access to the timeshare and have never complained if they lose out on $ because they cancel... they know the restrictions ahead of time.
I do hate how Hyatt nickels and dimes for transactions, including changes to the guest on the cert... but it is what it is.