This is literal retard shit. If they had searched the house looking for drugs, and found only legally owned guns, it would indeed be improper to launch criminal charges based on that. However, having found drugs, the presence of guns was then an additional crime. Since Nick, being an absolutely retarded cocksucker, had them just lying around in his master bedroom full of drugs, a number of doctrines come into play.
One is plain sight. They were just lying around everywhere. Another is inevitable discovery. Once drugs were found, obviously the search would continue to find more. There is no way such a search would not have turned up the guns too.
And since guns+drugs+kids=an entirely NEW crime, this was just going to happen.
Nick is retarded. His whole defense is retarded. Robert Barnes is retarded. The Barneswalker is retarded. Viva is a retarded Canadian Jew.