Sitting out because you might get injured is fascinating to me, as an argument, because if you accept it as a premise then you should be equally fine with a player sitting out in any situation where it applies.
So, a player who's projected to go in the draft would be okay sitting out the CFP championship game, or a conference championship game, or all of them, and so on. If you really don't have any problem with them sitting out, then it should be fine for them to sit out no matter what. You should more or less advocate it, really, as it will always be the optimal choice for an individual seeking to maximize profit in that setting.
I wonder how fans in general would accept that, or what that would do to the game at that point. And what the implications would be for the sport. Maybe any college sport. If you're projected as a first round NBA prospect, you probably shouldn't play in the NCAA tournament, either.