Judicial Qualifications Quotes
This was more than a general observation at the time. Elena Kagan had just gone through difficult and extended Senate confirmation hearings to be a Justice of the Supreme Court. She was confirmed but there was a substantial Conservative opposition to her on the grounds that she had not served as a judge, although she had appeared as an attorney in many cases and as Solicitor General of the United States she argued cases before the Supreme Court. To many it was surprising that a sitting justice would so currently take a public position which could be interpreted as criticizing one wing of Congress, especially since that wing had been criticized for just playing petty politics and having no real substantive issues.
In America, the best attorneys have stayed in private practice where they could make much more money than government service or become professors and scholars of law. In either case, most have a track record that would make Senate confirmation difficult even if they wanted to be Federal Judges. A few like Abraham Lincoln went into politics. The Supreme Court is somewhat of an exception because of the power it wields, but even then many great attorneys have not been so inclined. Federal judges have usually been above average as attorneys, but not among the greatest.