chief-Hey here's an idea TF2C. Instead of trying to stop people talking about competing services, why don't you go ahead and provide a better service to keep your playerbase? If you don't, everyone is just going to jump ship once those services come out and then your site is dead.
Their service isn't bad. The TF2C website overall is pretty good, it's just let down by the fact the administration/developer team consists of people who are socially inept and can't communicate with the playerbase at all.
You say one bad thing in their chat and they take it as a personal attack, either due to some language barrier (which often results in them not understanding irony/sarcasm it seems), or because the power that comes with their admin rights has gone straight to their head.
If you can't tolerate someone saying 'competing service X looks pretty interesting', you're better off just staying out of public relations completely.