LOL
You're nuts. It's not ok for a DEA agent to be armed in the commission of a crime. Which is why he was indicted with a gun charge. According to your idiocy, it would have been legal for him to brandish his gun while robbing a bank.
But seriously, you obviously know the law better than prosecutors who have charged him. You should call them and insist they drop the charges because he was a federal agent.
Then you should call the DEA since you clearly know more than them and kindly explain to them he was wrongfully terminated since a federal agent can go commit a crime anywhere because they're always on call.