To prepare chutney, combine first 4 ingredients in a small saucepan. Bring to a boil over medium-high heat. Add rhubarb and the next 4 ingredients (rhubarb through ground red pepper); reduce heat, and simmer 5 minutes or until rhubarb is tender. Spoon into a bowl; cover and chill at least 2 hours. Discard cinnamon stick.
To prepare pork, combine jelly and mustard in a small bowl; set aside.
Combine 1/2 teaspoon salt, black pepper, and cumin; rub evenly over pork. Place pork on a grill rack coated with cooking spray; grill 4 minutes on each side or until desired degree of doneness, basting occasionally with jelly mixture. Serve pork with chutney; sprinkle with green onions, if desired.