Greetings!
The answer to your question is a hard one to assess because of the limited amount of info that we have of his law practice pre-watchtower days. (not too mention the inherent subjectivity)
Rutherford has gotten criticize for allowing the (mostly honorary) title "Judge" to be used because of his limited service in that capacity, but Rutherford had several years of law practice under his belt before he encountered the truth. It was a couple of sisters that came into his law office one day and sold him the Studies in Scriptures. Not soon after this he expressed his interest, soon became a believer and not long after accepted a position at Brooklyn Bethel eventually becoming the Society's principal lawyer and then also V.P.
Rutherford probably was a middling lawyer in terms of litigation and such but given his power of oratory he was from that viewpoint, probably a pretty good one. Rutherford did take the lead in arguing before the United States Supreme Court for a few of the JW cases (along with Olin Moyle and then Hayden Covington who soon took over as the principal WT lawyer respectively.) I don't recall his exact record but for one of the Supreme Court cases that he argued it was not ruled in favour of the Witnesses.
Nevertheless, to appear before the U.S. Supreme Court a lawyer must be in good standing and is also usually a pretty good lawyer in that you have to be able to address the Justices interruptions and questions on the spot.
As for his training, the admission to law in those days was very different then it is today and we really cannot say that because the requirements and progression was different then that it was worse. Indeed it was probably better back then in some ways. In any case you would have to disqualify all lawyers and judges prior to the modern system in that case.
As for your citation, assuming it is accurate, this is really not a big deal. Then and now lawyers are cited for contempt of court for all sort of things. This might be bad behaviour or it might simply be getting under the judge's skin, being too vigorous in pressing a point, or disregarding a prior instruction. Even good laywers get sanctioned or cited for contempt of court.
As for his death that the poster above mentioned, that story is a fabrication. Rutherford died quietly on his deathbed in Beth Sarim. Fred Franz, Nathan Knorr and Hayden Covington were all there and received a "passing of the mantle" ala Elisha-Elijah according to Ray Franz in CofC.
-Eduardo Leaton Jr., Esq.