I don't believe Houshalter was referring to proving Friendliness (or something along those lines); my impression is that he was talking about implementing an AI, in which case neural networks, while "scruffy", should be considered a legitimate approach. (Of course, the "scruffiness" of NN's could very well affect certain aspects of Friendliness research; my relatively uninformed impression is that it's very difficult to prove results about NN's.)