don't post in it (unless you have an important follow-up or question exactly on-topic, and the topic is still recent). If you post just a comment on something somebody said ... chances are no-one will care because it's been a while since everything was posted.
Well, I see this as an important follow up since there are people that seem to miss the very point I was making, it was very relevant to the thread, and although the topic was not recent there is obviously someone who cares.