How can anyone think that he is a nutcase?
Well, when he says good things about the Constitution and the Bill of Rights, he is telling the truth. When he says that TIME magazine and the major TV networks are trying to tell Americans that religious freedom and other basic rights are out of date, that's when he goes wrong.
Yes, things have changed since the days of the Founding Fathers. In our large, crowded, anonymous cities, and with the police being tasked with protecting women and children from domestic violence, as well as having to deal with the extreme violence of drug pushers, it's not surprising the Second Amendment is being questioned. And the realities of national defense in a nuclear world have meant that Americans pay more taxes than they once did, and that America has a standing army in peacetime.
But the solution isn't an absolute rigidity in running the country as if it were 1800. The answer is for Americans to ensure that their politicians and Supreme Court justices understand the principles behind the Constitution, so that such amendments as are needed from time to time won't have the cumulative effect of eroding away the liberties of Americans.
His concern is legitimate. How he presents it, and the details of his position, are what are doing his concern a disservice.