Actually, looking at the authors list, there's only a couple who have left the freelancers pool completely. A number of them aren't as active these days though. Several are working on their own projects or working for other game companies, and others have just stepped back for whatever reason.
Freelancing is a weird thing. People bounce in and out, back and forth all the time. I know i had some burn out toward the end of the 3rd edition, and other than some playtesting of early 4th ed material, I was completely out of the pool for about 4 years. Sometimes it's just family obligations or your "day job" taking up more time, sometimes it's burn out, sometimes it's frustrations with the fan base, and sometimes it's just lack of inspiration or boredom. Freelancers come and go pretty regularly.
Critias was obliquely referring to some problems that CGL had a little over three years ago now. I won't go into it because it's not relevant, it was over three years ago, and if you really want you can find out more than you likely care to by doing some web searching. And while that situation resulted in several freelancers leaving the company, it didn't have much impact on the published author pool for this book.
That said, I didn't work on the book and don't really know the answer to your question. I've never used Hong Kong for anything, so never really read up on it much. Sorry.
If you really want, I can make up an answer. But it wouldn't really be canon. Nor would it necessarily be well researched, as I'm hip deep in several other projects right now.
Bull