In a medium saucepan, bring 2 cups chicken broth, 2 Tbsp. butter and 1/2 tsp. salt to a boil. Stir in quinoa, cover and return to a boil. Simmer until liquid is absorbed, 15 minutes. Fluff with a fork and set aside.
Season skinless side of fish with 2 tsp. salt and 1/2 tsp. pepper. Pat skin side dry with paper towel. Heat oil in a large, nonstick skillet over medium-high heat. Place fish fillets in hot pan skin-side down and sear for 5 minutes. Turn fillets gently with a spatula and cook on other side until flesh is opaque, 1 to 2 minutes. Transfer fish fillets to a plate, tent with foil and keep warm.
Wipe oil from pan and reduce heat to medium, then add remaining 1 Tbsp. butter. Add tomatoes, olives, garlic, thyme and lemon peel. Increase heat to mediumhigh, add wine and cook for 4 minutes. Add remaining 1/3 cup chicken broth, sugar, and remaining 1/4 tsp. each salt and pepper; stir well. Sprinkle parsley into sauce.
Spoon quinoa onto plates and place sea bass skinlessside up on top. Spoon sauce over fish and quinoa.