I have finally had a skype text chat with the main Chinese Bitmain software engineers and unfortunately it's precisely as I predicted. In principle they wanted to help decentralise and saw p2pool as the obvious way to get involved and would be good publicity for them. Unfortunately they spent a lot of time fixing their regular pool first and just left this announcement up almost as a "preorder for a better p2pool". However they misunderstood the issues with p2pool and thought that all it needed was more coding expertise and manpower contributed to development to fix it and have only just started investigating it now.  While they can clearly improve on the existing code - and probably will unless the project gets canned - after I queried them about what solutions they had for the intrinsic p2pool protocol limitations/problems, they had precisely zero valid solutions for them.