for what it is worth i now feel compelled to give my two cents worth on two other issues
1. I think it is okay and often valid to bring up a poster's history if it is relevant to the thread in question. The same often happens in real life (as it should); part of how you chose to judge a situation with a friend/coworker/child/etc will be based on your knowledge of how that person has handled similar situations in the past.
i do, howver, think there are ways of bringing such thinsg up that are resepctful and ways which are really rude. I see both on the dis a lot and much prefer the respectful route
2. It seems to me that a pm makes sense when, for example, you want to alert someone that they might want to remove identifying information from a post without alerting the rest of the internet to that information's presence, or if you want to send someone your email address, etc. Responding to the information that the conversation in a thread is about but choosing to do it privately even though it is relevant to the thread as a whole seems odd to me and almost either cowardly (too afraid to have "everyone" see you opinion) or aggressive (going after just that one poster). What was posted did not seem like anything that needed to be in a pm.
i would not want to respond to that in anything but a public fashion either--so it was clear that i was not engaging in inappropriate insults, etc. I doubt i would have posted it, but i would have posted that i would be happy to respond to the issues in the pm publicly if publicly asked or something along those lines.