For what?
For ruining his day, people have gotten huge judgments for less.
From the Six Flags: Great Adventure website:
DRESS CODE
In keeping with our family-friendly atmosphere, and for health and safety reasons, Six Flags strictly enforces a dress code. Proper attire must be worn at all times, including shirts and appropriate footwear. Clothing with rude, vulgar or offensive language or graphics is not permitted, and shirts cannot be turned inside-out as a solution. Bathing suits may be worn only in water park areas. Park admission may be denied if clothing is deemed by management to be inappropriate.
I saw nothing rude, vulgar or offensive about his shirt, only a real pussy left wingnut would be remotely offended.