Basically, its a flooder, not a ddoser/doser. I tried to the flood a server (using the method that i think he is using) and basically failed. But still managed to find out a small piece of the solution. The player connected to the server is not a cs client. He found a way to bypass current server anti-flood/security. Idk how he did this, but im almost 90% sure that he is using this method. What Id suggest for HS is:
The first thing HS should try to do is to find out how he managed to "fool" the server, and then, maybe they will find a solution to block him again.
(Id also suggest to check a bit on dproto)