Actually, there is more than one issue mentioned here. It looks like the option to disable this setting is already available for people who purchase PowerDVD 12 now (in build 1905 non-trial installer).
However, there is also another bug too mentioned in this thread. I am curious if the "inconsistency bug" will be fixed too? This refresh rate changing option only shows up sometimes. It's too bad the developers for PowerDVD 12 don't actually use this product at home or they would have noticed something this obvious.