I count trying to connect someone's alts together as doxing, since it violates the right to anonymity. If someone's made the choice to leave their name behind and establish a new identity, I say give them a chance. Let them be forgiven, don't tie them to their past.

But I don't think it's unforgivable. If I did, I'd be a huge hypocrite. I think everything can be forgiven if there's a commitment to do better.

(I do think exposing someone for sockpuppeting is acceptable, but that's a special case)