President Trump's pardon was issued while there was already a motion in place by Arpaio's legal team to overturn his conviction. The pardon seemingly made this whole legal process moot, but in fact Arpaio's legal team is working on a strategy to make the pardon moot (for the reasons they've outlined here).
What makes this so bizarre is that the judge has ordered the U.S. Justice Department -- who prosecuted the original case against Arpaio -- to file a response to Arpaio's motion to overturn his conviction. How the hell are they supposed to respond here? LOL.
If I were a DOJ lawyer working on this case, I'd be tempted to give up my legal career and get into something more honorable and useful ... like selling heroin.
LOL!