There are a number of different ways that work. Two factors most people don't really consider with carbonating sweet cider is that if you're doing it in a keg, the keg is able to withstand more pressure than a glass bottle, and that it'll likely be stored at a temp not conducive to further fermentation. Cold crashing, filtering, and even using potassium sorbate are not going to kill off or remove all of the yeast. It will create an environment where any fermentation that happens to take place will be so slow that you will not notice it. The only sure way to kill yeast is through pasteurization. The only (relatively) sure way to remove yeast is by using a very fine filter (and a quality one).
That being said, it is not necessary to go through great lengths to remove the yeast unless you are storing the cider in bottles in a medium temperature room (60-70F). The method you choose will be fine. Many people have different methods and the one you chose is fine. Wine makers do that all the time, using potassium sorbate (and potassium metabisulfite) and sweetening it after it stabilizes. The only feature you'll be adding to this is force carbonation.