In a large saucepan, saute shallots and scallions in olive oil until translucent, about 2 min. Add basil, olives, tuna, lemon zest, and lemon juice. Season to taste with salt and pepper and stir until well heated. Set aside and cover to keep warm. Meanwhile, bring a large pot of water to a rolling boil over high heat. Add pasta and 1 Tbsp salt and boil until al dente. Drain pasta and add to tuna-olive mixture. Toss well and briefly reheat before serving.