I'm not following the logic here either, what motive does the Republican Mueller have to scapegoat his parties president, He's been a closet democrat his whole life? Also, if we had to have solid proof before an investigation could go underway with an interview, How exactly would you build enough evidence for something like, oh let's say, murder, to start an invesitgation? Also, If you have the evidence at that point why have an interview, just to throw an extra charge on if you lie about it?
Let's think also for a moment, if this was all happening in North Korea, and a high ranking party member were to have dealings with, oh, Bill Gates. Would the charges against them be lowered because it was just Bill, and not a more powerful person or someone in the government? I don't think the sentiment of treason or at least an affront to the nation would change in that situation.
What if we look into which Russians and find that trump was dealing with the mafia or a huge mover in their economy, and not the government, does it really make the situation better at all?