Heat 1 tablespoon oil in a large nonstick skillet over medium-high heat. Add the shrimp and cook, stirring once or twice, until just cooked through, about 4 minutes. Transfer to a bowl and cover to keep warm. Add the remaining 1 tablespoon oil, 1/2 teaspoon cumin, 1/2 teaspoon garlic powder and 1/4 teaspoon salt. Stir to combine. Add cauliflower rice, scallions and water. Cook, stirring, until tender, about 5 minutes.