Social justice warriors sometimes say they only want everyone to be nice, but their definition of "nice" is deference, not niceness. Nice people treat each other as equals. Where everyone respects everyone, no one defers to anyone, except in the most general way of taking turns.
But concepts like "derailment" exist to enforce deference; equals are willing to test each other's ideas. Concepts like "white women's tears" and "the tone argument" can only be called nice in the bizarroverse of SJ Warriordom; in the rest of the world, the kindest way to describe them is rationalizations of rudeness.
Malcolm X understood that speaking truth forcefully does not preclude consideration for others. He said, "Be peaceful, be courteous, obey the law, respect everyone." He understood that for the truth to be heard, it must be spoken with respect. I don't know if he would go this far, but I like to think he would: To speak truth without respect doesn't just disrespect the listener—it disrespects truth itself.