But - there is NO law that requires people to be nice.
"No but ..."
"Do I say something degrading about you?"
"No, but I don't feel uplifting, I feel difficult, uncomfortable."
"We need to be polite and discuss matters that may affect our life. Why should I care all the time about how you feel? Why should YOU care all the time about how I feel?
"Because ... ... you need to be nice!"
"Because! ... I'm leaving! You are impossible!"
If someone gets so easily upset, that one simply should not go any close to politics (or management, or any professional field that requires communication with other people, really: for more follow to “Intellectual stagnation, social conformism, and the crisis of logical communication”).
Confusion between "polite" and "nice" is not confined by politics, one can see it in science, in business, basically everywhere where people talk. In politics it is called "political correctness", in other spheres it may be called "rudeness", or "cynicism". Unfortunately, this confusion presents a huge obstacle to forging an effective collaboration.
this is one of my favorite Russian wisdoms (more in a different post):