I think it's being handled quite well considering bhw is one of the largest forums in the world and can still remain up. Just hope this gets resolved soon.
based on my experience working with sites against ddos attacks, rarely does a simple ban illicit such a reaction such as a prolonged attack. Most attackers believe it or not are actually more interested in being able to claim they successfully brought down one of the largest forums in the world. Another possible suspect could be major competitive underground networks that may have something against bhw or gain from the downtime
of bhw.
tl;dr it's unlikely a few members who were banned would go to the extent to ddos bhw (nor do they have to means to)