Heat pomegranate juice in a small saucepan over medium heat until reduced to 1/4 cup. Set aside. Meanwhile, let the chicken come to room temperature for about 30 minutes. Heat oven to 450 degrees.
Brush chicken with oil and season with salt and pepper. Tie legs and transfer to a large ovenproof skillet.
Roast chicken, turning once, until golden and cooked through, about 50 minutes. Transfer to a serving dish and brush with reduced pomegranate juice; let stand 10 minutes. Deglaze skillet over medium heat with stock, scraping up brown bits with a wooden spoon. Cook until reduced by half. Strain fat. Add thyme and pomegranate seeds. Serve with chicken.