Actually, the free breakfast benefit is only for weeknight stays, not weekend. Since your stay was for a Saturday night, the hotel does not have to provide you with any type of breakfast.

Cut and pasted from the T&Cs: "Guaranteed Concierge/Executive Club Lounge* access applies to regular hours of operation at Marriott hotels, JW Marriott hotels and Renaissance hotels worldwide. For Marriott hotels, JW Marriott hotels or Renaissance hotels without a Concierge/Executive Club Lounge or if the Lounge is closed, the guest is entitled to receive a free Healthy Start Breakfast, Monday through Friday."

The above text can be found on Marriott Rewards Terms & Conditions