Drain oranges and pineapple, reserving 2 tablespoons pineapple syrup. Gently press oranges and pineapple between paper towels to remove excess moisture.
Beat cream cheese at medium-high speed of an electric mixer until creamy. Gradually add reserved pineapple syrup and milk, beating until smooth. Fold in 1 1/2 cups whipped topping. Gently fold in orange-pineapple mixture and 3/4 cup coconut. Spoon filling into crust. Cover; freeze until firm.
Let pie stand at room temperature 20 minutes before serving. Dollop remaining 1 cup whipped topping on top of pie. Garnish, if desired.