More to the point, if you cannot find evidence of a crime, untill conviction, the basic premises is to hold an accused as innocent.  Writing the way he did, is an affront to the foundation on which the system of law rests, innocent untill proven, beyond reasonable doubt, guilty.  The question then becomes, why did Mueller write as he did? To pander to the DS Base? At the very least it provides a skyhook for the D party to continue painting themselves in a corner.