Yeah, it's a TOS item:
"Group Buys can not be promoted on Head-Fi's Main Forums, or via Head-Fi's Private Messaging, without first receiving authorization from Jude via Head-Fi Private Messaging or e-mail. Please note, though, that it is not our desire to see Group Buys used by Members of the Trade as a primary method of distribution and advertising on Head-Fi's forums--so, for this and other reasons, they are usually not approved. Exceptions may be made on a case-by-case basis, and most often for DIY-related parts that might otherwise be unreasonably difficult to obtain."
I thought it'd be something more Hifiman-related, e.g. Hifiman issuing a statement that they won't allow the new units to be sold at prices significantly below MSRP or something. They still might enforce this though.