Last night I finally sat down and did some study. Fang Zhouzi's ghostwriting accusation against Han's <Triple Door> reminded me of Michail Sholokhov's <The Quiet Don>.
There has been accusation of plagiarism against Sholokhov. Some don't believe he possessed the skills and experience for to produce such a great piece of work. However this accusation has been remained a mere "accusation", and most likely will remain so.
Though I pretty much concur with Fang's analysis, to prove the accusation is unlikely if not impossible.