File this away under "myths programmers believe about language," with some bullet points like,
- A word or symbol will always have one meaning.
- Okay, but at least those meanings will stay the same over the next decade.
- The next year?!
Words change meaning because your present-eyes are different from past-eyes.
The gun symbol has changed meaning because your present client is different from past clients.
In my opinion if the people that changed the gun emoji had done it by introducing a new watergun emoji, replaced the gun with watergun on the keyboards, and declined to make their devices capable of emitting the sequence of bytes representing the gun, I would have been fine with that, and for their preening purposes I think that would have been sufficient. I'd consider that annoying and rude, but not malicious. If you have a unicode text file with the gun emoji, and you don't know when it was written, you genuinely can't tell what the author wrote as a symbol, even ignoring all the complexities of language, almost as if the word was blurred, and you can't tell between two possibilities.