Chongqing was in the news well before the email. Bo Xilai was on a trajectory to crack into China's Politiburo (9 most powerful in Chinese govt). He cleaned up Chongqing but did so through an iron fist and great corruption in the beginning years.
Connection in HRC emails is worth checking out but seems likely to be noise. Beijing didn't know what to expect from Bo. Many rising ranks in Chinese gov are grandkids of the Mao regime. The grandkids want to revert back to Mao so China should be dealt with as such