DH (who has celiac) actually did have steak at brunch! (This was on the Wonder.) He got that and a fish dish off the menu. Iirc, they had to adjust a side for him, which wasn't a big deal. Our server made it sound like they would make practically anything he wanted off the menu work, at least for gf. I wouldn't think there is an easy way for them to do the things with tomatoes sauces for your husband, but as long as he doesn't pick those items - I imagine they'll work with him doing things like subbing something else for the potatoes, etc. Those things are all made to order, so they're easy to personalize.
Yes, they did make a special dessert for him too. It was a giant, gorgeous sorbet thing. He could eat the chocolate covered strawberries on the buffet as well. Honestly think a couple other things should have been fine, but I guess they were worried about cross-contamination in the prep area.
For the appetizer buffet - I will say that was the hardest part. There was a lot that is gf on paper, but for anyone sensitive, just not going to work. All the cheeses are gorgeous, but displayed around lots of bread and crackers items, so that was a no-go. He went heavy on the cold seafood, as it wasn't near glutens on the buffet tables and wasn't something people could easily have contaminated. It actually would be nice if they offered to make up a plate in back of stuff that *should* be safe but isn't under the circumstances b/c of all the guests helping themselves and cross-contaminating things or that are just displayed in a contamination-prone way (like the cheese). It wasn't offered like dessert was, though, and DH doesn't like to make a stink. He didn't leave hungry with the 2 entrees, in any case! Definitely encourage that for your husband. I knew from here that plenty of people order 2 entrees and it's no big deal, but mine needed encouragement b/c he didn't want them thinking he was asking for special privileges or something.