Well, this is literally true if you consider non-human lives. The danger I see is then not listening to and interacting with these non-vegans to develop a more nuanced perspective of the people on "the other side" who may not be very different after all. Stating a legitimate political or moral view alone is not (itself) what induces polarization, as I see it.
Calling the other side "murderers" goes beyond "stating a legitimate political or moral view". You're accusing the other side of being criminals of the worst kind, so of course it's going to be polarizing.
Can you explain your reasoning for this?
More specifically, if one only considers certain types of X to qualify as X, does calling someone X if they perform an action not universally considered to be X go beyond "a legitimate political or moral view?"
If you want redefine language, that is fine, but in real life I will not accept being called a murderer.
1984 was not a manual.
What do you mean by not accepting it? You're welcome to disagree with the classification, of course. That's how we start a hearty discussion on values, morals, politics, etc.
In real life, I would also hope that I use a more tactful strategy that doesn't immediately fall back on a term that will polarize my interlocutor.
I will make sure you will never call me a criminal of the worst kind ever again. In my experience, not very much is needed.