Boma is a great buffet, for breakfast or dinner. It has something for everyone.
That said, there is plenty on the menu at Jiko or Sanaa that is not very spicy. The server is there to steer you away from spicy dishes, too.
You should be fine at any of the three places.
But if you want to just walk around the resort, stroll and look at the animals on the savannahs, not feel locked into an "exotic" table service (they're not as exotic as they look!), there's always the Mara, quick service at Jambo house. That's pretty much a typical quick service, with most of the usual resort QS options. Mara is not as amazing as the 3 table service, but to me it's far better than a some resorts' table service, if you can believe it (looking at you, Turf Club, Olivia's, GF Cafe, etc.)! And you're free to arrive anytime.