Ok lets look at your hypothesis:
'Chinese military personal likely taught Okinawans military arts to defend tribute vessels, and that these arts survive until today'.
So you have stated that Chinese military (Independent variable) taught Okinawans Military arts and that these Chinese Military arts survived until the present day. I assume that the dependant variable is the Okinawan martial arts practitioner. This is way too woolly for me and also very difficult to prove.
How will you isolate these variables from all of the other extraneous variables? The analysis of Kata may support the hypothesis, but I cannot see how it can be very empirical. Nevertheless its an interesting idea, but I will take a lot of convincing.
You state that 'Today we find that there are a number of ways in which Okinawan kata fundamentally
differ from Chinese systems practiced today'. You need to consider what the issues are of reverse engineering something when that is the case.
Just curious but have you actually studied any Chinese Martial Arts in which the spear is used?
Otherwise your point: 'If the kata movements donít seem useful in propelling a spear, then the hypothesis canít be supported. If, however, the movements of a broad cross-section of kata can be used to effectively propel a spear, then I would argue that this is evidence supporting the hypothesis'. Is this not highly subjective?
You also state that 'One must train in kata as spear kata, and do so intensively'. I suppose that takes me back to my the question, do you have any training in Chinese arts that involve spear, or have you observed any such arts. Personally I think it may be worth doing so.
You state that many empty hand kata movements do not make sense unless they are spear movements, I am unable to see this, certainly the Kata that I have studied I can find applications for the movements, but I cannot see how any of these realte to spear. So could you be more specific as to which kata you intend to analyse for such movements?
Many of your other points listed beneath your hypothesis are to mind a bit presumptious. However I do recommend that you look at some of the articles on by Gregory James Smits on this link: http://www.east-asian-history.net/Ryukyu/
You seem to be forgetting the history of Okinawa and the purpose behind the Satsuma invasion of 1609. The Satsuma were broke and not in favour by the Japanese rulers at Edo at the time, they needed Okinawa because of its merchant trade with China. This filled the Satsuma coffers, during Chinese state visits to Okinawa Satsuma military personnel were low key but they were nevertheless there. You would need to prove that those who worked protecting ships, such as Sagukawa and Matsumura were not under the Satsuma yoke. However I am unaware of any spear techniques in the Matsumura system.
There are still a number of issues about the tribute trade and yes it is possible that the Okinawans learnt Chinese arts, but these would have been in the capital. So you need to make a distinction between Northern and Southern systems. Many are of the view that any military arts that Sokon Matsumura may have learnt from the Chinese came from Northern not Southern China.
Sokon Matsumura seems like the most likely candidate to me to have studied anything military in China.
So you might want to look at General Yeuh Fei and the Eagle claw and also Fan Tzu Ien Jao in relation to Chinese arts as these clearly have a military origin, which is unlike much of what is to be found in Fukien. The Fukien is another variable that you need to take in to account.
You also seem to forget that much of Okinawa's written history in document form is no longer in existence, that of course assumes that it was in existence in the first place. Okinawa sufferred heavy bombing during the war which means a lot of stuff was lost forever.
Good luck with it.