Even if you didn't cite their names directly, their quoted posts would still show their names before it turned to AnonymousXWYZL. So, I think not citing their names doesn't solve the whole problem, if it is a problem in the first place. People delete their accounts for different reasons, maybe privacy is one of them, but if this is the case, then they can report the posts that reveal something about them before leaving.

I have my own view on how to handle things when a member deletes their account, but I think it's technically not straightforward if feasible at all. So, I will spare mentioning that