Having a good read, thanks for sharing the article.
The article explains some of the history neatly. The compilation of such information surely, I think, would make other or any upcoming Bitcoin users know Bitcoin history better, specifically about this forum. Since I personally did not dig down this forum deeper, there is information that I barely noticed, like the forum's finances.
Whether it's true that the hackers got access to the private messages or not. It's gotta be concerning for someone at that time if they have shared information including identities.
Although at that time there isn't any exact evidence, if the attack vulnerability itself is capable of accessing users' PM, it can be safely assumed the PM might also be accessed.