Mixter himself seems not to be too concerned with having written those tools, since he wrote them to prove a point, and to explore the possibilities. As he says, it is "Not very difficult" to write such tools, and the hosts used for such attacks are probably compromised through old and unpatched security holes.
Getting yourself a DDoS network does not take brains, any sociopathic 14-year old can do it, and they do. That, and the huge number of unpatched hosts on the Internet is worrying.
Oh, I nearly forgot todays laugh, "Phake Games 2". High quality stuff from Somethingawful.com. As usual I might add.