I just want to address this notion in particular. When a community chastises - or even ostracizes - a community member for harmful behavior, the way that person responds to these repercussions is a testament to their character.
To reenter that community, they will need to put in a shitload of effort to prove themselves worthy of being trusted again. They will need to contact those they’ve hurt and apologize personally and sincerely. They will need to hear how what they’ve done has harmed others. They’ll need to just accept it, and stop trying to explain why they thought it was okay, thereby validating their behavior. They’ll need to change their behavior and their words to show that they themselves have changed. It’s a lot of hard work, with no guaranteed result, but by putting in this work, they will be proving how interested they are in becoming a better person.
If, however, this person mutters, “Fuck it,” and, licking their wounds, they seek the shelter of other shitheads who wipe their tears and promise them vengeance, then good fucking riddance dude. It’s not a community’s responsibility to preemptively coddle shitheads for fear that they might become bigger shitheads when punished. Moriarty, the Google dude, and so on didn’t ‘turn’, they just figured out they didn’t have to wear the mask of kindness any longer. They never belonged in the first place. They were just pretending.
All I’ll say about Nick is that no one wants shitty people to remain shitty. No one has to accept his apology, or let him back in to their community, but surely everyone would like for him to stop being shitty. That’s entirely, completely on him now.