How is he sure that they had no knowledge?
What if they knew but were just waiting for someone with a blog or a Twitter account to make the "discovery"?
In any event, none of this would have happened if email addresses had not been collected.
There is no need to collect email addresses in order to allow internet users to post comments. Requiring email addresses serves no benefit to the user. It is just more gratuitous data collection. Data which eventually becomes the subject of yet another "data breach blog" entry.