"Ruled a nonvoter" doesn't make much sense. Either the person voted or didn't vote.
Student or Learner
I just read the following sentence in an online gazette "The death of 13-year-old Dylan Redwine of Monument has been ruled a homicide, and his father is a person of interest in the case." Can I use the verb "to rule" as in " A person has been ruled a nonvoter."?
P.S. Sorry for the typo in the neadline.
The death was ruled a homicide. Not the person.
A person could be ruled ineligible to vote.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.