I'm not arguing that it can't. I was merely pointing out the proper 'burden of proof.' The article was criticized for failing to demonstrate that something can't be done... that's not fair. The burden would be on the proponent of the proposition that a machine can attain general AI. That's all.
Perhaps there could be general AI... I'm not saying it can't be done. I would point out, though, that IF it is to be done, it certainly won't be by copying a brain. Nobody even knows the hell the brain works...
Maybe you are stuck on the notion of a computer as a silicon chip. Biological entities are just a special case of machine ergo it is already proved that a machine can attain general AI.