(EDIT: The article itself uses the word "sexist", so it might indeed have been a call-out. However, that doesn't affect my point that we should not tolerate shitty behaviour, no matter which label is attached to it.)
The moderator's behvaiour itself was inappropriate, no matter which gender the other person had, and no matter whether the other person is offended or cool with it.
Why? Because others might not be cool with that, and rightly so! If we publicly tolerate inappropriate behaviour, we are making it even harder for those who are not cool with it.
That's why we (the audience, the society) should not tolerate shitty behaviour, and speak out publicly against it. Not just to fix this individual case, where the affected person may or may not need our help, but to establish a culture where this shitty behaviour will occur less often in the first place.