No he hasn't faced responsibility since he's still on NS, never apologized for his actions and only attempted to use apologies to get back on the site. You aren't a victim, you're his friend, and have no right to speak on behalf of victims to what constitutes an apology.  He shouldn't be on NS at all in any way. Just because he committed the harassment over IRC and Skype doesn't separate the fact that his victims were selected from and chosen from the NS community and some are still members of this community.