China is one hell of a lot more competent than Russia
We have no real idea whether this is actually true on a military level as their military is even less tested in real world conditions than the Russians were. Even if they are, an amphibious assault on an island with the potential of the world's most powerful navy in the way is a lot more difficult to pull off than a land invasion.
AFAIK Mike Lynch was the highest net worth individual on the yacht and Reuters says his net worth is ~$450 million so there may actually not be any missing billionaires. (The Evening Standard claims he had a net worth of £986.4 million which would make him a billionaire in USD but rich lists are often BS so I'm going off what was claimed in court)