That archive date I linked is from shortly after his death. If you go through the various archive dates you can see that he made changes to the page over the years. He added the bit about wanting a violent overthrow of the government when he was 18 or 19. In 2007 when he would have been 21, the archive just shows a note that he had a server crash and the site is gone but you can email him if you want a copy of it. By the time he was 22 he’d put the site back online. He made more edits visible through the following years until his death. So yeah we don’t know his thoughts but we do he continued to maintain that page, even choosing to restore it after a server crash, until the point he killed himself. It’s not as though it’s an online post he made as a kid and forgot about.
I wonder if this is why so many sites now started including previews of new content on old content pages. It’s made trying to google by date range completely useless because google now thinks a 12 year old post is brand new because there’s a preview of a new post at the bottom when they re-index it.