On Bill Maher last night they were saying that it's not really about Arpaio but he's sending a message to everyone in the Russian collusion that he'll bail them out even if they get convicted of anything. It kinda makes sense.
I disagree. If you're looking at it that way, you're not thinking like Trump. For Trump, it's definitely about Arpaio.
First off, Arpaio is his buddy. They've been personal friends for years. Second, Arpaio is the personification of Trump's "build the wall" rhetoric. As far as Trump and the Trumptard base are concerned, Arpaio is a hero, a patriot fighting back against the brown horde that's taking over the country. They think that Arpaio was, as Trump put it last week, "convicted for doing his job." It's disgusting, but that's what they think.
Trump has felt strongly about this all along. Trump wanted Jeff Sessions to get the case thrown out of court. This matters to Trump personally, and it matters to the core Trump voter. This pardon is wildly popular with the Trumptard voter base.
Paul Manafort or Michael Flynn, on the other hand? They don't matter to the Trumptards. The only people who'd really support a pardon for Manafort or Flynn are Trump himself and the immediate families of Flynn and Manafort. Pardoning Russian double-agents would be a lot harder to sell to the voting public than pardoning an 85 year old "patriot". The core Trump voter might accept it, but I don't think anybody else would. And the Trumptards on their own don't have enough votes to win elections. They need the support of the undecideds and the never-Hillary voters and the non-votes of the apathetic.
The pardon of Arpaio might hand seats in the House of Represenatives and an Arizona Senate seat to the Democrats, as latino voters will come out en-masse against the Republicans in the 2018 mid-terms elections. Pardoning Russian conspirators would only worsen the situation for Republicans.
-k