You make valid points, but I don't see them as being true of government lawyers. Government lawyers are paid on a GS scale, usually 12-14, so the money motivation isn't there. And I don't remember the last lawyer, government or whatever, that was interested in the truth. So if their motivation isn't political, they must be pretty unmotivated.
Great points Sarge. And to also bring in a little of Confluence's points, the motivation here is purely law. They want to study and get better at their profession, while upholding the American judicial system. A lot of them transition to high paying jobs in the private sector, once their requirements for years and duty are met. Political affiliation only comes into play if you are going for an elected position. If not, you are working for the constitution and the country.
Politicians and pundits, seem to me, to be the only ones who are purely driven by political affiliations.