This is exactly as stupid as changing it to a water pistol in the first place was
1: Page 12 of https://www.unicode.org/charts/PDF/U1F300.pdf (search for 1F52B)
I'm not saying they're further out of spec. But I disagree with your implication that they are somehow further in spec than a water pistol. Pistol is pistol.
Yes. If I asked you to bring me a gun (or a handgun) I don't think anyone would argue I might have meant a water pistol. A water pistol is a gun-shaped object, or an object that imitates a gun, but it isn't a gun.
If I ask you to bring me a gun, and there is a water gun right next to you and you argue that "I might have meant water pistol" (colloquially: refusing to assess the water gun as a "gun"), I would assume you were ignorant, dishonest, or both.
The same is true of the gun emoji. Hard for me to picture a scenario where I would need to communicate "real gun" but not want to say the words "real gun". And given the ubiquitous (until now) change in the icon, I have empirical evidence that it was an entirely practically appropriate solution. And, again, it was no further out of spec than an M1911.
Various knives are available if you want it, so if anything we should add MORE emojis (gun combining character something else = various types of gun, say).
In fact, it's easier to have one "known bad" emoji to check than having hundreds to look at.
Conversely though, the decision to change it back is probably driven by trolling and attention-seeking more than anything.
If we have older communications that use an emoji, it can retroactively edit the meaning if that emoji renders to a fundamentally different object than it used to, so this kind of change has the side effect of rewriting history unless people take extra care to only use fonts that match the age of the document.
It's already hard enough to communicate clearly and effectively in the modern world without having the rug pulled out from under us with stuff like this.