That'll go over well.
"Hey, after school we should sneak up and [squirtgun] John, Mary and Pete!" sent on an iOS devices will turn into "Hey, after school we should sneak up and [handgun] John, Mary and Pete!" on other devices.
One of these statements implies a prank. The other implies murder.
Maybe Apple should work with the Unicode Consortium to declare additional emoji, such as a squirtgun, so that they can drop the handgun emoji from their keyboard and replace it with the squirtgun.
As it stands now, they're just swapping the graphic of a lethal weapon with a children's toy and crossing their fingers that no horrific misunderstandings occur...