This makes a good point about what Arpaio’s pardon and the timing of the pardon means for the Mueller probe:
It (Arpaio’s pardon) being expected, though, didn’t do much to lessen the surprise at its occurrence. That was in part because of the timing: dropping the news right as the most serious hurricane in half a century was making landfall in Texas on a Friday evening. But even more because of what Arpaio was being pardoned for. Arpaio was convicted of contempt of court after being told to stop racially profiling Hispanics in his county but continuing to do so anyway, in part to bolster his reelection bid. This was a law enforcement official who was ignoring a federal court order and, as a result, was convicted of a misdemeanor.[…]
In other words, if any of Trump’s allies decides to tell special counsel Robert Mueller to stick his subpoena in the south side of the National Mall, Mueller can press a court for contempt charges. The person could be convicted of those charges — and then get a pardon identical to Arpaio’s.
So we can expect Trump to can Mueller and/or pardon people some busy weekend in the future. Just like Nixon did on that one Saturday night.