China doesnt use a handful of pf rules, they use a comprehensive array of filtering, DPI, and firewalling techniques. They've been known to actively probe VPN services to determine whether they are allowable, implement real-time updated keyword content filtering, and forge RST packets for any "undesirable" content.
They are also incredibly proactive about nullifying workarounds; ask the Tor guys how their efforts with e.g. obfsproxy and obfs2 went. Really good at circumventing the GFW for a year or so until it ended up 100% blocked just like stock OpenVPN.
Either way its difficult to defend the idea that China intentionally did this
No, its not, it fits 100% in with their existing (bad) relationship with google.
when google gladly censors their search results and complies with all local regulations.
Your information is about 5 years out of date. Ever since the Aurora hacks in 2010, Google has ceased all cooperation with the Chinese government on that front, and has ceased filtering on their end. They have in fact on a number of occasions worked to alert users when third party tampering has occurred, which has led to a number of confrontations with the Chinese gov't. Notably, in June of this year, China completely blocked Google prior to the TIanenmen Square anniversary.
Google remains a sterling partner of the chinese leadership in their quiet, tacit business participation in what for all intents and purposes amounts to a capitalist dictatorship with a communist logo.
Except for the part where they are the one major internet company NOT cooperating with them, while Microsoft and Yahoo continue to do so. Hope you dont use Skype over there.