I think this is a ridiculous change by Apple, going completely against the idea of Unicode and consistent character displays across different devices. Author's suggestion is good, but I don't think that this was a necessary change by any means in the first place.
Unicode only says that it's a gun, and only recommends how it should look. IME's are free to make the emojis look however they want at their discretion. Note Samsung's saltines instead of chocolate chip cookies for "U+1F36A Cookie". Consistency is laudable, but we live in a world with multiple cultures, meanings, and contexts, so in the end consistency might actually be more harmful and reductionist.
The unicode code chart¹ actually says “PISTOL = handgun, revolver”, and the reference glyph (with a larger version on page 4) is pretty clearly a Beretta M9.²
① http://www.unicode.org/charts/PDF/U1F300.pdf#14
② http://www.beretta.com/en/m9/ and https://en.wikipedia.org/wiki/Beretta_M9
Apple is not alone though. On windows i get a colorful lasergun:
http://i.imgur.com/bOC6M6H.pnghttp://emojipedia.org/microsoft/windows-10/pistol/
Additionally, your pointing out that the example glyph looks like a beretta only has any kind of weight if you can also point to guidance that specifies to what level it should be followed.
I would operate on the condition that the standard denotes that items representing the unicode can be flavored/styled to the producers desires, but should not misrepresent the item/object being conveyed. A water gun != a pistol and a laser gun != a pistol. Both are altogether different items/objects. If Windows/Apple want unicode for those objects they should appeal to the standards board to make it happen. It would be acceptable to hide the pistol emoticon in their UI while still allowing it to display correctly when used. Masking it as something it is not is just misleading though.
That is your preference, however the question here is what the unicode consortium thinks.
Why have a standards body at all if it's just going to be up to the 3rd parties to determine what is going to be displayed then? Like I said before, they should be free to display each unicode item/object artistically how they see fit, they should however not be free to change what item/object is to be conveyed entirely.
That is your opinion and you are free to hold it but what matters here is what the Unicode Consortium thinks.