But isn't that the point of the person you are replying to?

Its the meaning of the ideas being communicated not individual glyphs. A gun emoiji does not neccesarily mean "lets shoot up the place". A water pistol is similar enough to a gun that anyone who has that meaning in mind can easily just use it and be understood. Or they could just use something else with an understood meaning. After all, many emoiji have context specific meanings. An eggplant is not just an eggplant.

Its just downright silly to ban things at this level of abstraction. It wont stop people talking about guns.