i agree with your post completely bar the above point. OW was due to induce MU but, as the story goes, in the same period CX took over KA so some bigwig in CNAAC felt OW got already their local airline, and gave the green light to comrade chairman Liu Shaoyong and his backers in Paris and Amsterdam to scoop MU to Skyteam. Since the whole KA affair was organized in Beijing basically to save an almost bankrupted CITIC (the then mayor shareholder) I would not discount the whole matter being suggested and/or urged by certain European diplomatic circles well introduced in Beijing, very keen to reproduce in one of the most forecasted growth market the comfortable duopoly already present in the continent.
I always felt that MU membership is the most shaky about the ones in China now. It is only a matter of time, probably when Liu is moved on to another position or god forsake it, goes through a rough period, before MU will be extracted from ST and reassinged to another alliance. OW probably it is placing their stakes for the occurrence, and this would avoid the embarrassment to go upfront with CX over Hainan membership.