Douglas Metzgar was convicted of violating a city ordinance…

Douglas Metzgar was convicted of violating a city ordinance that prohibits any person from committing any “indecent, immodest, or filthy” act in the presence of any person. Mr. Metzgar was convicted after someone, standing in the parking lot of Mr. Metzgar’s apartment complex, observed Mr. Metzgar standing naked in the front window.  Which of the following is the best Constitutional argument for Mr. Metzgar?