"If a player has 2 non-exhausted units, only one of which has a valid move to make, that player must spend their turn moving that unit, and then on their next turn rest, as described above."
Pretty sure this doesn't say what you want it to say. What if making that one move frees up the other piece to move? Do they still have to not move it and then rest the following turn? Instead, what if moving the free one doesn't unblock the other, but then the opponent's turn frees up the stuck piece? Is resting still forced? I don't expect anyone would think those reasonable or intended, but that's what the rule is saying.
Also, I'd add in a statement saying it's explicitly okay for a player with only one non-exhausted piece that can move at the start of their turn to move just that one piece and not be saddled with having to rest the following turn. (After all, the first player's third turn pretty much has to do this.)