In my opinion, not prosecuting a blatant criminal is a much worse look for the country. You can't undo the past, but you can bring him to justice.

Not prosecuting a ex-President for literally trying to both violently and by subterfuge overturn a lawful, democratic election while in office by a position that is literally sworn to preserve, protect, and defend the Constitution would officially make America a joke.

Other democracies can uphold their own laws even when the highest official of the land violates their oath of office. If we do not, the idea of America as a democracy is officially dead.