Preheat oven to 400ºF (200ºC). To make glaze, combine pomegranate juice and maple in small skillet set over medium-high heat. Bring to a boil then reduce to a simmer 5 to 10 min., until reduced to about ⅓ cup (75 mL) and consistency of maple syrup. Stir in thyme.
Season salmon with salt and pepper. Place salmon on parchment-lined baking sheet and brush with pomegranate glaze. Bake 18 to 20 min., brushing with collected juices half-way through, until fish flakes easily with a fork.
Meanwhile, make sauce by mixing sour cream, dill and horseradish. Serve salmon with sauce spooned over top.