The Unicode standard does specify explicitly that U+1F52B stands for pistol (handgun, revolver), so while you are free to replace it with whatever you want, replacing it with a water pistol means you are purposely creating ambiguity where non existed.
For a vendor of operating systems that is not very responsible behaviour.
I disagree. Again I say that the description is deliberately brief, to allow some latitude on the part of the implementer.
> you are free to replace it with whatever you want
No, with a pistol.
You seem to be arguing that a "water pistol" is not a "pistol". I agree not all pistols are water pistols, it is also true that not all pistols are revolvers.
If you choose to depict a pistol that is NOT a revolver, I think we would agree this still satisfies the standard. I think that a water pistol is a pistol, I think it is stretch to argue otherwise.
For a vendor of operating systems that is not very responsible behaviour.