A few comments.
First, we moderators are assigned to specific forums. While we can kill spam and ban trolls in any forum, we otherwise do not moderate forums other than the ones that we are assigned to. Also, moderators are not separate from the board. We are regular SDMB members, just like you. So, while there are moderators participating in that thread, they are not moderators of the IMHO forum, and their posts should be considered as regular posts. Moderators have opinions on various topics and are free to express those opinions, just like everyone else. If they want to “get in on the act” (as you put it), they are free to do so, just like anyone else.
If a moderator is acting as a moderator, and is not just posting as a regular user, they will usually clearly indicate that they are doing so.
Second, I can’t speak for the other IMHO moderators, but the main reason I did not moderate that thread until just before posting this was that I was busy and hadn’t had a chance to do much moderating at all yesterday. We do have lives and jobs and stuff outside of the SDMB (believe it or not), and sometimes we can’t devote as much time to moderating as we would like to. My apologies for not being able to get to the thread in a more timely manner.
Third, when someone posts something, their history on that particular topic can be very relevant to what was posted. Context often matters. I do not have the time to read through all of the posts and threads that were linked to regarding past posting histories and such, but bringing up the OP’s history on a particular topic is not necessarily an attack on the OP.
As for the thread itself, perhaps if I had been able to get to it sooner I could have steered it back into IMHO territory, but given the GD style arguments and the lack of focus on the OP (not too surprising given the broader topic that spawned it), I felt that at this point it was best to close the thread.
Again, apologies for not being able to respond sooner.