Isabelle, I’m very aware of the experiences of historically or contemporarily oppressed people. That comment in the original essay, however, refers to people who do not, in fact, belong to such groups, and still take offense at other people’s opinions when they disagree with theirs. Not exclusive to certain quarters of the Left to be sure, but frequent enough to deserve mention.
As for Stoicism, it is not at all a bizarre choice. The Stoics were adamant that when one takes offense the choice is entirely up to that person, because if one instead decides to ignore the offense then the latter becomes air movement that does not affect others. That’s the Stoics take. Whether people wish to adopt it or not is, of course, up to them.