Marriott sent this email to Huffington post in response:
"We are aware of the picture that was tweeted. It shows an offer that was made independently by the hotel and not the Marriott Hotels brand. As far as we know, it was limited to one property. While the hotel was making a sympathetic gesture to its guests in remembrance of 9/11, we apologize and understand why some people may have misunderstood the intent of the offer. We are reminding our hotels to use discretion and be sensitive when remembering major events such as 9/11."
The photo was uploaded from twitter when a hotel custy was puzzled by the sign.