Gun registration works my friend. Just ask Hitler, Mousolinni, Stalin, etc.
First off, he should have demanded to see a warrant. Secondly, he needs to get a hold of a good 2A lawyer and fight this. If he wins, I would suggest that he considers relocating to anther state, preferably one that believes in the RTKABA.
If I have to explain why I ride, you wouldn't understand. Explaining sex to an alien would be easier than explaining the feeling, one that boils all that is going on in your life down to what really matters each time you are in The Wind. All I can say is, Life is not Life without it.