He has to fill the court with federal judges that have been appointed by a President and approved by the Senate. That's a somewhat higher standard than whoever.
I wish more people understood this... I keep seeing comments about being appointed with no oversight... there was oversight when they were approved by the congress(Senate). If they aren't fit to be on this court, then perhaps they aren't fit to be federal judges.
Perhaps there are people one would trust to be judges when there's a full public record of their proceedings, but not when those proceedings take place behind closed doors with no public oversight.
My problem is the proceedings taking place behind closed doors and without any real oversight. Especially since DOJ/NSA/FBI have been outright lying to congress.