I can't imagine that there would be a valid Constitutional claim against the business for enforcing a dress code, save for if the dress code itself was per-se discriminatory. If, and it's a big if, the dress code was put in place because the intent of the dress code was to keep a specific class or demographic group, who is protected under the 14th Amendment, out of the establishment, then that's a different story. Either way, if the APD used the language, as the article purports, and it was the officers' intent to remove him based on his ethnic, religious, etc... status, then it could be an interesting case. If the proprietor actually did ask the officers to remove him, and based their rationale on his dress code alone, then they were likely performing a trespass removal, under the color of law, and aren't liable for those actions. The fact that the establishment denies asking for assistance in removing an 'unwanted patron,' doesn't put the APD in a good spot.