I really don't know where this phenomenon of trying to appear calmer, more detached, and impersonal and therefore more 'valid' comes from. Is it a sexist echo of masculinity=rationality/femininity=emotion grating on society's collective ear? Is it weird post-enlightenment bourgeoisie elitism equating feelings with baser needs and the lower class, and stoicism with spirituality and reason? I really don't know and it's a pain.
If something is really important to someone else, they are not going to be calm when you step all over it. People are not going to be calm when you condescend to them. All you are proving is who has the luxury of not being affected by the issue, not who is more valid in their ideas or not. Not who has fewer pesky feelings, but who of us is the best at hiding them for the sake of making the other look foolish; a personal attack without saying a word.
Impassioned people are not the same as incoherent, unreasonable people. Impassioned people are not the same as upset people. The best way to make an impassioned person upset is to say that their feelings are a weakness, are childish, are invalid, when they are what give them conviction and strength.