Very interesting, although that post does heap plenty of skepticism on it. Interesting as heck, though.
I would also like to add that JamesP81 is right... superintelligence isn't the issue nearly as much as what a "dumb" computer could do under the control of bad human beings.
Does the brain even "compute" deterministically, like an Intel CPU? Or does it converge using myriad neuronal feedback loops on a match between an apparent "goal" and its apparent satisfactory conclusion? Enormously inefficient perhaps from an electronic engineer's point of view, but remarkably capable,of that there is no doubt. The threat to "wetware", of course, is the blinding speed of modern electronics.