I really like these two paragraphs towards the end: Being kind isn’t the same as being nice. It isn’t about superficial praise. It doesn’t mean dulling your opinions. And it shouldn’t diminish the passion with which you present them. Being kind is fundamentally about taking responsibility for your impact on the people around you. It requires you be mindful of their feelings and considerate of the way your presence af…
Of course it costs nothing to address people in a way that they feel comfortable with, so you should do it. But, in a Postel's law sort of way, in terms of critiquing argument I don't think it's worth dwelling on the tone. Two plus two is four no matter how many times the person arguing it uses the word "fuck", to put it crudely. And often, addressing tone is a way of eliding real argumentation.
It doesn't cost nothing, it's costs a lot of time and attention to find out what they're comfortable with and much attention to filter yourself to to fit that, so no you shouldn't just do it without a good reason.