Revealingly, the central function of the Constitution as law--the supreme law--was to impose limitations not on the behavior of ordinary citizens but on the federal government. The government, and those who ran it, were not placed outside the law, but expressly targeted by it. Indeed, the Bill of Rights is little more than a description of the lines that the most powerful political officials are barred from crossing, even if they have the power to do so and even when the majority of citizens might wish them to do so.
It's almost hard to imagine anything more undemocratic than the view that political officials should not debate American wars in public, but only express concerns 'privately with the administration.' That's just a small sliver of Johnson's radicalism: replacing Feingold in the Senate with Ron Johnson would be a civil liberties travesty analogous to the economic travesty from, say, replacing Bernie Sanders with Lloyd Blankfein.