do you know of any other bitcoin forum/resource with such significant influence like bitcointalk allowing promotion of ponzi sites?
What exactly would be the argument here? BTCT is supporting X because BTCT allows it and has 'significant influence' while others don't? No, I'm not familiar with similar forums because they're mostly filled with conspiracy rubbish (e.g. HF fanatics). As far as Bitcoin forums go, BTCT is the most popular one, yes.