I wrote an answer about this awhile back that may be of interest: https://www.reddit.com/r/AskHistorians/comments/2200dc/if_i_was_an_average_american_citizen_either/

If you have follow up questions, let me know -- I'm not around my books right now but I can look up Pike County later. Ping me in a day or two if I forget.

So after doing a bit more research, I can state a few more things with some confidence. Pike County stands out as it is a river county, being just south of Hannibal of immortal fame, and was home to a fairly large population of slaves -- something between 25 and 35 percent in the decades before the war. There were enough slaves in the county that a "Little Africa" developed there, in a former town called Hartford (there's currently a New Hartford because Hartford was destroyed in flooding) where newly freed African-Americans congregated after the war. So if your ancestor was a judge, he was likely (obviously) a member of the white elite, but his sympathies would be tough to suss out without knowing more -- as I wrote in the post linked to elsewhere in the thread, even the white planter elites in Missouri were generally (more or less reluctant) Unionists.

This page actually offers a surname search, which may be of some interest to you. The State Historical Society of Missouri also has an indexed newspaper database, which is unfortunately fairly limited online, but they have in their collection quite a few newspapers that operated in Pike County before and after the war on microfilm. Here's a list for Pike County specifically: https://shsmo.org/newspaper/newspapercatalog/pdf/pike.pdf