Yes, TDPK has tried to tell the court that because Aaron Walker cannot represent himself in federal court in Maryland because he is licensed as a lawyer in DC and Virginia.
Here’s what Congress had to say about that in 28 U.S.C § 1654:
In all courts of the United States the parties may plead and conduct their own cases personally or by counsel as, by the rules of such courts, respectively, are permitted to manage and conduct causes therein.
Here’s what Local Rule 101.1.a of the U.S. District Court for the District of Maryland says:
Individuals who are parties in civil cases may only represent themselves. Individuals representing themselves are responsible for performing all duties imposed upon counsel by these Rules and all other applicable federal rules of procedure.
Thus, it would seem that if Aaron Walker qualifies as an individual he may represent himself in a civil case (such as the RICO Madness) in the U.S. District Court.