@JustineMumsnet, for the love of God, please stop posting. You look more unprofessional and passive aggressive with every comment.
It doesn't matter if the OP is Hitler reincarnated. As a user of the site, s/he is entitled to the same data protection as the reincarnation of Mother Theresa. Reposting deleted comments when there are other ways of reassuring site users that there was no malicious intent and of contacting the OP is snide, immature and gobsmackingly unprofessional. This isn't the twee 'round the kitchen table' amateur operation any more, it's a multi-million pound business and as the CEO, you're damaging your brand by acting like an aggrieved sixth-former when the fact is it's YOUR IT fuck-up (again!) that has potentially placed users of your site at risk.
At the very least you should replace the post in which you quote the OP's comments with the "message deleted - quotes deleted post" standard MN moderation message while you concentrate on putting in place the necessary measures to minimise the chance of this happening again. I recommend a thorough overhaul of your database structure and employing some system testers who know what they're doing.