This isn't harsh at all. Merely just.

As each who joins the group, has sworn an oath before all of the gods, to never seek to play this role in the group, the one driven away is an oathbreaker, not to be welcomed back. At most, we will help him seek a way to expiate his guilt, so as not to have to face Nemesis in this life, or the Erinyes in the next. But we would no more welcome him back to the group, than we would invite a recovering alcoholic to join us down at the bar. He should not return to the scene of that earlier failure to resist temptation of his, that cost him his honor.

Given that he will have committed an impiety in the eyes of all of the Olympians and the Cthonic deities as well, he might do well to keep a low profile in his dealings with them henceforth, anyway.

Let us be clear, though that this expulsion isn't for the minor transgression of someone being a little pushy or a little sanctimonious. For that, gentler correction and the submission to a little semi-ritualised teasing to make somebody take himself a bit less seriously will suffice. Here, we are speaking of someone who has truly tried to take control and claim an elevated status for himself.

Returning to our previous discussion.