He was convicted of a misdemeanor. That's one step up from a traffic ticket. Not exactly the kind of thing that drives our justice system or has any measurable impact on Trump or his presidency.
I don't think anyone should be pardoned because of political affiliation. Pretty weak straw man you set up there.
Do I think age matters when it comes to minor offenses and how much time and resources we devote to it? Of course. This guy has outlived the life table charts. He probably isn't going to live much longer. I haven't really followed his case closely, so I don't have an informed opinion, but it does appear as though some politics was at play here. Wouldn't surprise me if the Obama administration targeted him. Don't know if that's true, but wouldn't surprise me.
Overall, seems like a whole lot of weeping and moaning over a molehill. One of my friends was saying before the pardon that if Trump pardoned him it would be some catastrophic miscarriage of justice. 
It is a crime and he was found to be guilty. And it is exceedingly difficult for a cop, let alone a "sheriff", to be found guilty of a crime with all the protections, immunities and power that they have. Should the people who were jailed or imprisoned in Arpaio's facilities for misdemeanors have been released? Should they have been pardoned?
Do you think political affiliation did not play a role here? Do you think Trump would not pardon David Clarke or another conservative outspoken cop if he committed crimes but he would otherwise pardon some outspoken liberal cop for similar things? Would you think political affiliation would not have come into play if Obama had pardoned Hillary? The pardon is an arcane relic that can be abused and rarely serves to correct the many injustices of the "justice" system.
I don't care if Arpaio is old or young or he dies in a week or lives another 20 years. If he is old and frail that is too bad for him but per his slogan "if you don't want to do the time, don't do the crime". He should not have done the crime and after so many years of "enforcing the law", he should know better about that than an average citizen. No one should be above the laws, especially those who "enforce" them, the laws should apply equally to everyone.
