Don't worry, I'm just as confused and afraid as you are.
George Zimmerman claimed self-defense when he shot and killed a young, unarmed man named Trayvon Martin in 2012. He was acquitted of all charges and now he's selling the gun as "a piece of American history".
Maybe his confederate flag business isn't doing so well?
Bidding starts at $5,000 and he is literally planning to use some of the proceeds to fight Black Lives Matter activists, or as he put it according to the video "fight [Black Lives Matter] violence against law enforcement officers".