If he wants to apologize, then that’s what he should do. It has nothing to do with any of the rest of us.
Similarly, if he does apologize, then it is up to those who receive the apology to decide if they want to forgive. If he remembers nothing, they may not want to forgive, but then again, it may be enough just to hear the sincerity in his voice and know that he really feels bad that his former self did this, even if he didn’t remember it.
But there are no shoulds here. Up to him. Not up to anyone else.