Holding each ear of corn upright in a deep bowl, cut kernels from cobs. Rinse scallops and pat dry; sprinkle lightly all over with salt and pepper.
Melt 1 tablespoon butter with 1 tablespoon olive oil in each of two 10- to 12-inch nonstick frying pans over high heat. Add corn, bell peppers, garlic, and cumin to one pan; add scallops to the other. Cook, stirring both pans often, until vegetables are crisp-tender, about 3 minutes, and scallops are browned on the outside and barely opaque in the center (cut to test), about 5 minutes.
Just before serving, stir basil into the vegetable mixture and cilantro into the scallops. Add salt and pepper to taste to both. Mound vegetables in a wide, shallow bowl; top with scallops (and any pan juices).