That's good material then. Confucianism certainly fits several of the definitions of religion that exist in multiple dictionaries. I don't see the holes in the argument for its inclusion in civ IV then...it fits definition-wise and in terms of # of followers...and in terms of historic significance.
Part of me wishes they were all pushed up. Sure, "choose religions" can change which 2-3 religions dominate per game, but I'd like to see a greater variety in games...where say sometimes 2 religions take over as currently happens, but in other games even 5-6 are viable and cause a lot more hatred.