probably not for long
You have to take into account that these are the players that have kept their original username, not gone incognito. Most of the top players change their usernames regularly now, so they won't ever be on this list.
I just noticed that most of Triad don't appear anywhere high on the list, and some of the strongest players are below me. So high score alone doesn't indicate skill, merely acquisition of things the grepolisscore places value on.