Preheat oven to 400°. Line a rimmed baking pan with aluminum foil and spray with cooking spray.

In a small saucepan, heat oil over medium-high heat. Add garlic and cook for 30 seconds or until fragrant, stirring frequently. Stir in pomegranate juice, orange juice, sugar, thyme, orange zest, and crushed red pepper; heat to a simmer. Reduce heat to medium-low and cook for 5 minutes or until thickened and reduced by half, stirring occasionally.

Place salmon, skin side down, on the prepared pan and sprinkle with salt and pepper. Brush salmon with 2 tablespoons garlic mixture; roast for 20 minutes or until internal temperature reaches 145°, brushing with remaining 2 tablespoons garlic mixture halfway through cooking.

Serve salmon sprinkled with walnuts and pomegranate arils, garnished with orange wheels and thyme sprigs if desired.