Can PC 245(A) (1) assault with a deadly weapon be dropped PC 211 robbery?

My son found a man in his yard wandering around and asked him what he was doing there the man replied I'm lost don't worry about me. My son told him he needed to get off his property the man ignored him my son then said did you hear me the man came towards my son so my son grabbed him by the shirt and escorted him off the property. After he found the man had dropped his wallet near phones out if his pocket during the altercation my son went to the neighbor’s house to tell them there was a strange man running around the property. When the neighbor said that was a man she was going to rent a room to. My son then apologized and gave her the items found telling her they have had recent burglary's and he thought the man was up to no good. He was very sorry for what happened then the police came to my sons house an hour later and arrested him and charged him with these to penal codes 245 (A) (1) assault with a deadly weapon.