I feel like the colors in general don't really mean much now. Back when the site was more sectioned and we had the old karma system (which was also before there were so many represented games), the colors generally referred to how helpful/knowledgeable the posters were within the context of one of the game boards. Not to say the cross-site forums didn't have their own community on top of that, but the forums were a lot less fluid between games.
I think what's probably important to note there is that, for many people, that game forum was the reason they began posting on Zam. So you really started at default (iirc) for one game.
After they added more games, WoW in particular, we started drawing more and more posters from the other sites, which made things more muddled. Someone who gained guru on the XI forums might not have known squat about WoW. Furthermore, people who might become extremely knowledgeable about one game might have had a pretty significant post count on a forum for a game they were newbies for.
Plus, as you post more, your overall karma is less affected by ratings.
So lowbie colors doesn't really bother me anymore, because I stopped seeing the ranks as a sign of knowledge within that community a while ago. Now I generally see it as a measure of general pleasantness. And even then, color vs. no-color is the biggest distinction. If you reach 100 posts without having gained scholar, you probably aren't someone we enjoy hearing from.
Even if he reached guru, his overall post count would still be low enough that it would be affected by ratings if he wasn't a quality poster. So it shouldn't bother you. He won't keep the color if people rate him down. IDK if karma has a relation to post count itself, though, so no clue if posting more without rating up or down would change things.
And now I'm rambling, because I'm avoiding a paper.
Anyways, you all are horrible, @#%^ed up people