Grand Isle on Fulton a review & some annoyances a tad long

Took the wife and kids downtown yesterday and started with lunch at Grand Isle on Fulton St. When we walked in, we were promptly seated. The place on the inside is really cool lots of sinker cypress panelling and old fishing pictures. They have a decent local beer selection. Wife got a really well made Bloody Mary. The wife and I both started with the smoked fried oysters with a garlic aioli sauce. These were perfectly fried in smoked flour, and the sauce was fantastic. For the main course, I had the shrimp and grits. It was a very unique take on the dish. Shrimp were perfectly cooked atop well made grits, but the sauce was a white gravy style sauce with andouille. It was good. Wife had a huge shrimp cocktail that she said was perfect. Food and service, A+. Now for the annoyance. About midway through the meal, the waiters started setting up a huge table right across from us. The large group walks in and is seated. They start reading the menu, which I believe states that gratuity is added to the check on large groups. At this point they get up and start splitting up and try to sit at random tables through the restaurant. They start making a scene about the food( which they hadn't tried), and what the menu was lacking. In the end only five of the people stayed to eat, and sat at two separate table right next to one another. This fiasco went on for nearly 30 min. Is it that hard to tip 18 %? Manager handled it well, but it was aggravating to watch knowing that they were just trying to stiff the waiter.