both children and adults need to be able to regulate their own emotions in order to cope with the challenges of building competence in a new area
I strongly disagree with this claim. Regulating your emotions makes you dull, and apathetic. While in arguments, yes, you should stay away from emotional arguments and claims because they are not factual, however, arguing itself is the emotion. It is how you feel about the piece you are writing and defending, the passion, that there itself is emotion that shouldn't be regulated. Critical thinking doesn't require such emotional intelligence or control, but rather being able to fluctuate it and allow it to improve your writing and your voice.