This is completely incorrect. Black-holing is the process of announcing a more specific route for the host pointing it at a null0 interface. In effect they superceded the DOS, and at that moment became the progenitor of a larger scale DOS against Blue Security. Been there, done that, many times. They mitgated bad traffic, but also denied good traffic.
Blue Security, (which should have considered a name that didn't acronym as BS) should have considered the response they were going to get. To redirect the traffic really shows these guys as ameatures in the Internet business. All that aside it is time for some ISP's to step up and offer the bandwidth to liquidate this problem. If these guys want to go to war with spam, more power to them. ISP's deal with router-crashing DOS loads nearly every day. Having one that is predictable shouldn't be an issue.
-psy