It reeks of favoritism. As Sheriff Joe was only guilty of a misdemeanor, it's not like, say, letting Marc Rich off the hook. But Arpaio never showed mercy to anyone. "Blessed are the merciful, for they will be shown mercy." (Matthew 5:7) Somehow, Joe Arpaio doesn't come to mind when I think of this.
What's sad is I had a very devout coworker who once referred to Arpaio as a "hero" of his for the specific reason that he humiliated his inmates, many of whom *were not convicted of anything*. It always disgusted me, that level of hypocrisy.
I wish more saw things the way you do. Arpaio deserves no mercy from the state after his horrific abuses of the law, and I hope he gets sued out the kazoo in court.