The biggest problem with this avenue is that it is past time for filing to be on the ballot...
But maybe an injunction could be posted on that point as well.
A three way race would be interesting...
Federal case law is already clear on state laws for ballot access of federal office seekers. The state deadline for filing doesn't matter as long as there is plenty of time, the candidate is substantial and the state has no compelling interest to enforce their deadline which in this case it doesn't.
Basically state election law is allowed until the federal courts say it's not allowed. And in this case federal case law says the state deadline for filing as it applies to McDaniel is not allowed.