I had this same experience with the liberty hotel in Boston. See thread on this.
If you contact the lurkers I'm sure they can help and correct the error. The only problem is that in all likelihood, the hotel will simply remove itself permanently from C&P in the future (forever).
Once the lurkers corrected my reservation, the Liberty hotel has NEVER shown cash and points again...
So the answer is if there is no MLOS for the hotel/other rates then they can't impose one just for C &P. But if you get it corrected and honored, you'll probably never see C &P again at that hotel.