That they're only going after the first two seems reasonable. If the first had an incorrect copyright number and the second was too short a notice, fine. But they don't even touch the third notice, so it seems as though they're accepting that one is valid.
Now we see the full wording of the claim it looks like disney is just trying to have the soonest two dates thrown out on technicalities, but is resigned to the third. So unless they renegotiate, expect the rights to revert by 2023