Conversation has being going around in circles for a while now. Making an attempt to summarize:
*OP is right to believe that his wishes for privacy were mishandled by the hotel.
*mitigating factor: OP could have been more proactive in double checking his wishes were on record, rather than relying on 15 month old instructions being remembered.
OP has 2 options now
1) You wish to keep using the hotel if possible and avoid hassle of switching loyalty.
Answers:
-write a clear complaimt to corporate stating what you expect in the future, demand guarantees.
-optionally, ask for compensation you deem appropriate.
-when staying in the future, double or triple check when checking in that your privacy is guaranteed. Demand written statement if possible. Use an alias if necessary.
If you are not happy with guarantees offered switch to 2)
2) switch loyalty to another hotel.
-do still make your demands very clear and obtain guarantees in writing if possible, each stay.
-optionally try to obtain compensation for hyatt in form of a partial refund or something that wont bind you to the hotel.
for extra peace of mind:
-test the hotels! Have a friend do a fake stalk and see what happens.