McDermott carefully handled the question and was correct in his response. Me thinks you can't admit to dressing a player with concussion issues that you think shouldn't / couldn't be out there physically, even if your intent is to provide the player with an extra week of rest / healing out of an abundance of caution. I imagine the intent of the injury rules are to dress players that are physically able to play in the game without restriction, especially as it relates to concussions.
McDermott was playing it both ways with Morse in my opinion (i.e. he was cleared medically and available, but would only be put into the game in an emergency as a method to give him another week of rest to get his brain right). McDermott just couldn't admit that.