Personally I think that pretty much everything that can be said about this hypothesis has now been said. Like you my time is also limited, I have a philosophy and critical theory course to prepare to teach this coming semester, so I am going to be busy with that whilst running the dojo.
I agree that if the spear was significant in Okinawan classical kata, we most certainly would have seen it by now, it would be known. As you say it is not sensibly represented in kobudo either. The nearest we get is from Matayoshi Kobudo with Tinbe and Rochin. We see spear in Motobu Ryu Udun Te but it is not related to Karate Kata and there are many issues about that anyway.
As we know the use of spear by Okinawans even in demos leaves something to be desired.
Given that Seitoku Higa collected all of the old kata he could find on the Island and has lineage to some older traditions, I think my comments on Okinawan use of the spear by Okinawan Karateka of old schools can be summarised by this clip: http://www.youtube.com/watch?v=oOukiIAnxSg
As you say, Jim, the burden of proof is with Mike, even if he does not prove his original hypothesis, he may come up with many good things.
So Good luck with it Mike.