In a sense, any prosecution of a political figure can be considered political. But what's the alternative? Treating political figures as immune from criminal prosecution? What would that mean for the rule of law? And what would that mean for our expectations of our leadership -- who, if anything, should be held to a higher standard as model actors for our society and our children?
The alternative would be for prosecutors to focus their attention proportionally to `severity of crime * prior probability of guilt`. In an ideal world, you'd see Democratic prosecutors going after Democrats and Republicans going after Republicans just as often as the opposite. But I have no clue how to get from our current world to that world.