That's weird, my guess is the guy is being punished for something. Judges sometimes handed out odd punishments back in the day, maybe the guy killed another mans horse on accident and his punishment was to sit on the horse in his best digs for all to see and ridacule... just my guess
Well, someone has come forward with a theory at least:
Dipple said about all that's known about the picture is it was taken at South Eighth Street and Indiana Avenue between 1876 and 1884 - based on the bridge over the Sheboygan River in the background and the lack of railroad tracks that were installed in 1884.
The city had laws on the books that required people to stay with their dead horses until they were picked up and disposed of, Dipple said.