Remy (and, I presume, Enchante) can adjust to dietary restrictions. My family asked in advance for a meal without meat, shellfish, bell peppers and mushroom, and had a wonderful dinner with each course selected by the chef. We just stopped by the host stand on our first night onboard and noted our restrictions on our reservation.
However, I agree with the previous poster that no vegetables at all and no seafood would significantly limit the value of the meal. If your party member really just wants “meat and potatoes”-type food, Palo would be a better option. If the special requests are limited to avoiding seafood and just a few vegetables, that would be more reasonable. If the aversion to vegetables is just a preference, it is possible the way Enchante prepares the vegetables would make them more appealing. For example, my daughter doesn’t usually care for gnocchi, but found the gnocchi at Remy to be melt-in-mouth delicious.