Combine the rice and 1 2/3 cups water in a medium saucepan and bring to a boil. Cover, reduce the heat to low and cook until the rice is tender and the water is absorbed, about 15 minutes. Remove from the heat and let stand until ready to serve.
Meanwhile, cut off a 2-inch piece of the pineapple and grate it on the coarse holes of a box grater into a large bowl. Stir in the ginger, vegetable oil, 1 tablespoon soy sauce and 1/4 teaspoon five-spice powder. Add the scallions and pork chops and turn to coat; let marinate at room temperature, 10 minutes. Rub the remaining pineapple with the remaining 1/4 teaspoon five-spice powder.
Preheat a grill to medium high. Grill the pork chops until just cooked through, about 3 minutes per side. Grill the scallions and pineapple, turning occasionally, until charred, about 3 minutes.
Roughly chop the pineapple and scallions and transfer to a bowl. Add the red pepper flakes and a splash of soy sauce and toss. Serve the pork chops with the pineapple salsa and rice.