Mike Hearn does address some valid concerns with the centralization of mining, which are often brought up by many core developers.
The 2 Problems I have with his comments concerning the scaremongering of "china controlling everything" are:

1) The reality is miners share power with many other groups and there exists a complex interwoven power dynamic between nodes, users, merchants, processors/banks/exchanges, developers, and miners. When developers discuss centralization of mining concerns among each other in private there is an understanding of these complex nuances already . Mike Hearn is being deliberately misleading about not discussing these complex power dynamics when he addresses the public. The public walks away from the article believing that a handful of developers and miners control the Bitcoin ecosystem which is patently false.

 2) Rather than focus bringing up xenophobic tribal fears when discussing China, he could have addressed the more underlying problem of mining centralization where the incentives have temporarily shifted to centralized mining and node count drop off. we do not know if this can be reversed and exactly how but there are several solutions to reverse this trend being developed.