Plain meat and potatoes, or will he eat exotically flavored meat and potatoes?
At the Polynesian, he should be ok with 'Ohana. The meat there is marinated and/or spiced, but not too heavily. No potatoes though - lo mein, veggies, pot stickers, and wings.
As for AKL, that could be a tough one. Boma has plenty of meat and potatoes, but seasoned in out-of-the-ordinary ways. Some people love it and others hate it.
They have a beef filet and gratin potatoes dish at Jiko he could order, but its an expensive signature restaurant and not a good choice if you have kids coming along.
I would probably keep him away from Sanaa. It's amazing food, but mostly Indian-inspired.
Sounds like places outside your resorts might be better choices, unless you want to stick to the resort counter services.