My 0.02.
Being pulled over for not using a "turn signal" is absolute BS and usually is used "as cause" to pull someone over. Once pulled over, a LEO can manufacture suspicion as a cause to search a vehicle. I assume that's what happened here as Martin wouldn't be so stupid as to consent to a warrentless search. In this case, the suspicion of having a plant was the cause....as f'ed up as that is. Martin has a Second Amendment right to possess a firearm, not that the Constitution matters anymore. He was hurting absolutely no one.
Martin is paying the price is for all of the pearl-clutchers and bible-thumpers that beg their masters for the illusion of "safety."