Counting cases per judge is a legitimate method of weighing workload only if the cases are drawn from a similar universe. Among the geographical circuits other than the DC Circuit, this may be reasonable, given that their appellate jurisdiction is similar in subject matter. But given that the DC Circuit handles comparatively few of the kinds of cases that the other circuits handle (having only a single subordinate district court from which to handle regular appeals of the type other circuit courts handle), but has a special role handling appeals of federal regulatory decisions, you aren't comparing like cases to like cases when you compare case numbers between the DC Circuit and the other circuits. You'd run into the same kind of issue comparing the Federal Circuit to other circuits.

Of course, I'm not at all surprised to see a News Corp outlet overlook a critical distinction that is inconvenient for the propaganda interests of the Republican Party.