I agree, Bruce.
Further, it would seem difficult for the hotel to argue that the BB can't be given until check-out, when the rate rules for the specific reservation include the check-in wording. All of my OTP reservations have included some version of the following:
MARRIOTT STAY FOR BREAKFAST PROMOTION - RESERVE AND PAY WITH VISA CARD AND RECEIVE $100 BONUS BUCK AT CHECK IN WHICH IS GOOD FOR A FUTURE STAY
At check in, I show the printed reservation confirmation page to the desk clerk (with the pertinent wording highlighted) and have had no problems, even where the first response is "at check out".