I dont think it only Sanji restaurant! I've seen a video on youtube where people sitting in a restaurant eating and all the sudden Bink's sake song starts and Cosplayers dressed as Straw Hat crew comes in and sings... Weird right?
That would be a little better since it's an homage to the whole crew rather than just the one character. I also realized after posting it's at Universal Studios Japan so it's not as odd as when I thought they opened a restaurant and had the waiter(s) dress and act like Sanji, rather there will likely only be one Sanji in the park as there is one Mickey at Disney World.
Would be kind of neat if each character got a building in the park, Choppers Doctor's Office, Nami's store, Robin's Library, Franky and Usopp could maybe share a garage, Zoro's gym, Brook could do a set, Luffy could be on a Going Merry or Thousand Sunny that you can walk around. Idk that might be cool.