I'm going to have to disagree. Generally when doing research on a service (e.g. before buying anything from it), you want any thread that claims the service is fraudulent to pop out at first glance rather than mix in with other discussions that are either inquiring or even praising the website in question.
Id say people use search engines rather than scroll through pages of subboards, which would make both our arguments invalid I guess.
In addition, having to make sure the service doesn't have a Bitcointalk account would add an extra layer of complexity that'd only suck up time and amount to nothing more than the scam accusation ending up in a different board.
Whoever opens the accusation would have to invest that time anyway if they want assistance in form of a negative rating.