Cook the rice according to the package directions.
Whisk together the maple syrup and mustard in a small saucepan over medium heat and bring to a boil. Simmer until slightly thickened, about 5 minutes. Remove from heat and set aside.
Heat broiler. Place the salmon in a foil-lined 9-by-13-inch baking dish. Season with the salt and pepper.
Cut the pineapple lengthwise into quarters, then cut each quarter into ½-inch-thick triangles. Scatter the pineapple and jalapeño around the salmon.
Brush the salmon with the syrup mixture and broil for 5 to 7 minutes or until it flakes easily and is the same color throughout.
Serve the salmon and pineapple with the rice and drizzle with the remaining glaze, if desired.