The name definitely does ring a bell to me, too. I recall him being quite reasonable. Now comes the easy part, I use our Message Board's search functions, and I find...
Green_Pikachu's profile
From that page, you can also click another link and read his most recent replies.
The last time Green_Pikachu was online was in June 2007 and the last threads he replied to seem to be called 'Politics and History (World, National, and Local Events', 'NFL 2006: The road to Super Bowl XLI' and 'Time to Revitalize'. However, he posted those replies in February, so for some reason, he turned silent until he completely abandoned TPM after 4 months.
The postcount of G_P is down to 5,343. But the main argument in making these threads without any arguments at all is that there are obviously 100+ of members who have more than 3,000 posts. No matter how much you think your postcount++ counts, the more posts you make the more attention you get.
But back to the question, why he and prolly a great deal of other users aren't around anymore, I think this post sums it up pretty much.
Now here G_P might be talking about just GSC, but we can extrapolate, perhaps. As I have a bit jokingly referred to in the recent past, there have been roughly 3 eras in the history of TPM. TPM Now (2020-), TPM Overdrive (2010-2020) and TPM Classic (2000-2010). Now this was an attempt to seem like a great historian, but even before 'Pyhätunturi' or the SPAM forum, if you will, was created, many, many people missed the old ways of TPM. We might even be talking about pre-2004 here.
Another options remain, of course, but most dedicated users have eventually let us know even after they had left this world behind...