My 18 month old likes to play cowboy and shoot guns, but SIL informed me this will make him a delinquent, lol?

My husband is a cowboy and we live and work on a ranch, so guns are a part of our life. My husband watches the western channel from the time he gets home until he goes to bed, and my son likes to point at the TV and at his daddy and say "pow pow" and my husband plays dead. Its a game they have been doing for a while, in fact I remember doing the same thing as a kid. My SIL saw him do this on a video I emailed and she had a fit telling me playing with guns and pretending to shoot someone is starting him off on the wrong foot. She is a teacher, and her child is perfect I guess, but what little boy doesn't like to play cowboys and indians? Is it wrong to let him play with toy guns with the holster, or let him shoot us with his finger and play dead?