"(his proposal to allow states to nullify federal laws or amend the constitution without Congress)"
Does this guy not know that the states already have the right to amend the constitution without Congress? That's what the calls for an Article V convention are all about! If he doesn't comprehend that, his take on anything else constitutional must be viewed questionably. His complaints are just repeats of the same litany we've heard before: people today are too stupid for it to work, it could run-away and destroy the Constitution, etc. These have all been addressed over and over; if you dogmatically reject an Article V convention you refuse to consider the responses to those complaints, and if you're open to the convention possibility you've probably already heard them.