So let me see if I understand this: the POTUS just invoked the law to pardon a guy who was convicted of ignoring the law that said guy had sworn to uphold, in direct contravention to directives lawfully issued to him by another member of the law enforcement community. And I'm supposed to respect the POTUS's invocation of the law to pardon the guy who was convicted of ignoring the law, because that guy did such a good job of upholding the law, which a court convicted him for not upholding.
Although, on the scale of 1-10 of bad things Trump has done, this is like a 3 or 4 as far as I'm concerned. Arpaio is trash, but he is out of office and an 85 year old man that was excused from what would have probably been about a one month sentence.
If the President had waited for sentence to be imposed and then, if that sentence included jail, commuted that sentence. This would had served the goal of not imprisoning an 85 year old. And it also would have recognized that the guy was found guilty because the facts supported that finding, and left his conviction undisturbed.
But this outcome, the way he did it is just a nasty, gristly bone to the more radical anti-immigrant side of his base.