@DisneyBound2017
One thing Disney is known for is how they deal with food allergies. For common allergies (peanuts, tree nuts, milk, shellfish) they actually have allergy friendly menus, so if your DH has one of the common ones, that's a starting point, and then you can go from there.
I agree buffets can be challenging. Family style can be okay. We did Garden Grill in January, and they brought me out my own special everything. My family ate from the main course, and mine was separate, as it would be at a regular TS. And I have unusual allergies in addition to my peanut/tree nut allergy, and everything was fine.
I would avoid Ohana and the Luau, though, with a coconut allergy. Simply because it's probably found in a lot of stuff there. A good alternative, if you still want to eat at Poly, is Kona Cafe. It's a regular TS. I have a severe pineapple allergy, so severe that even trace amounts bother me, and even though they have pineapple on that menu, 1. There's enough diversity on the menu that I can find something on the menu I can eat and 2. I've never had an issue with cross contamination. Oh, and it's also possibly my favorite breakie location on property.
Any to avoid? Well, obviously, if you look on the menu, and there's an abundance of foods your DH can't eat, then skip it. Some restaurants on property actually aren't operated by Disney, so some of them are iffy, but most are fine (they won't have allergy menus, but a manager will still be there to talk to you)
You should check out allergyfreemouse.com. They have lots of helpful information on there.
Bottom line, though, when in doubt, always ask for a chef or manager, and don't overstress about it, as Disney always will take care of you.