Yet, he said he stepped outside and there they were.
Maybe he had a secret gun inside he hadn't told his wife about.
As regards the question: “How did he come out of the house with the gun, when he didn’t keep guns in the house?” there is a logical answer. The article says he kept the gun in his vehicle. He probably had an attached garage (which some would consider part of the house). Perhaps he kept the vehicle locked and out of the sun in the garage. Perhaps after he saw the perps breaking in the house, he went and retrieved his car keys, went down through the kitchen, into the garage, unlocked the vehicle, retrieved the gun and went back into the house to see what progress the perps had made.
Other stories indicate he retrived it from the truck, which was in the garage, when the whole incident started. I would expect right after he saw the scum break into his neighbor's house.