I believe this is incorrect. Nowhere in the "10 Commandments of Gun Safety" will you find this tenet. You will find the commandment that states, "Firearms should be loaded only when actually hunting." If you're in the field, it's not poor etiquette to carry your firearm, or to possess it while posing for a photo. It just needs to be unloaded and handled in a safe manner.
No firearms in photos may be part of the criteria for photo submission to The Augusta Chronicle, but it has nothing to do with firearm safety. Like the prohibition on deer tongues hanging out, maybe it is a politically correct attempt to protect the general readership of The Chronicle from images they might find distasteful. I hope not.
John C. Huffman