This is natural reciprocal altruism. If I was bickering a bunch of calling names, I wouldn't mind receiving it back. But I'm going out of my way not to do so, so I'm less tolerant of receiving it.

Similarly, not every reaction someone has is a sign of personal weakness of them. Including "quicker-than-optimal to take offence." Focus instead on the ideas and not trying to force things into aspersions on others.