Heat 1 tablespoon of the oil in a large skillet over medium-high heat. Add shrimp; cook and stir for 3 to 4 minutes or until shrimp are opaque. Transfer shrimp to a bowl; stir in snipped thyme. Add remaining olive oil, bok choy, and tomatoes to skillet; cook and stir for 1 minute. Return shrimp to skillet; cook and stir for 1 minute more. Season with salt and pepper.
Serve shrimp and vegetables with watermelon. Squeeze lime juice on salads; sprinkle with thyme sprigs and, if desired, feta cheese.