Shellfish also isn't great for people that just don't like shellfish.
Anyway, you no longer need a jacket at Enchante or at any other adults-only restaurant on Disney's cruise ships. You can find the updated dress code on the website.
"Adult-exclusive restaurants aboard
Disney Cruise Line ships are elegant dining experiences. Guests are requested to dress in a manner consistent with the restaurant’s sophistication. Formal or semi-formal attire is recommended. Dress casual attire with a polished look is permitted (such as dress pants, jeans in good condition, collared shirts and blouses and lifestyle shoes). Clothing such as T-shirts, swimwear and sports attire is not permitted."
Gold members, too!