From a first glance at that screen I would say that the "treshold" is reaching the first rank.
You can see that all the pink names on that page showing the newest users, for whatever reasons, do not have a rank. While the ones that are "vibrating furbies" do have the regulair white colour.
Why some members don't have a rank, I don't know. I can't see any (in)consistencies between members that don't have a rank vs. members that do.
I personally also don't see why this would have been done on purpose.
The point of changing the regulair members names back to grey was that the name colour of someone with the new ambassador rank looked too similair to the name colour of a regulair user, wich could create confusion for new users.
Similairly, the rare users with pink names might be seen as seen as special members by other new members that do have the normal colour, making for more possible confusion.
But, yes. It would be marvellous if you could give the overlord of overlords a ring, since I deffinetly suspect that there's something wrong here...