“Tone of voice” is not part of the definition of Truth.
Truth is multidimensional and, as such, it is capable of being conveyed in a variety of forms.
So to suggest that one is incapable of modifying their tone, without compromising the Truth, is a cop-out.
It’s a way of saying, “This conversation is on my terms. I don’t care enough about your response to structure my speech in a way that is conducive to cooperative communication.”
Such an attitude is the rightful privilege of the one who holds it, just as the decision to walk away from such a person is the rightful privilege of the one who wishes to not be verbally abused.
Here’s today’s two cents:
Know your conversational rights. Respect yourself enough to engage only in forms of dialogue that honor your dignity. Others have the right to be honest with you, but you have the right to be honest with others about your personal standards for healthy interaction.