We haven't had official word from any of the ISPs involved.
Sounds to me like a mistake, or an excessively cautious response to the prior court order requiring ISPs to block access to TPB. This may be a different domain, and it may be hosted on a different server, but this is inextricably linked to TPB.
Promobay.org was just banned because it has a weak affiliation to a method of desceminating content, some of which could in certain circumstances be copyright material - but ultimately that is up to the USER and not the website to which promobay is related.
Edit: grammar.