Clever.Sure anyone can do that but most won't even know how to go about doing it and those that do will do so at a cost of possibly getting caught in a sting by LEO's or robbed and killed by the criminals selling them.
And if you do so successfully, what can you do with your black market items but hide them? Most will not even bother and just stick to their bolt guns just the same as those who don't bother and stick to a semi auto receiver now instead of going the black market route of getting a receiver with a 3 round burst on the selector lever.
I sure as hell wouldn't want my kids having to do that to own a modern rifle just because a large group of people decided they don't like Trump's mouth and would rather vote for Johnson to get the Libertarian Party funding for the next election insuring Hillary becomes president and appoints an Anti 2A SCOTUS.