Season scallops on both sides with 1 teaspoon salt and pepper. Heat 2 tablespoons oil in a saute pan over medium-high heat. Add scallops (work in batches; use remaining oil if necessary, depending on size of pan); cook until golden brown and caramelized, about 1 minute on each side. When cooked, pour off any fat remaining in pan. Set aside scallops on a plate covered with foil.
Return pan to heat. Deglaze pan with sherry, scraping browned bits from bottom of pan with a wooden spoon. Simmer until sherry is reduced by two-thirds. Add stock, butter, saffron, thyme, and remaining 1/2 teaspoon salt. Bring to a boil; add couscous. Cover the pan; remove from heat. Let sit for 5 minutes. Uncover; fluff with a fork; adjust seasoning if necessary. Serve with scallops.