I think you're missing the wider picture here, in your eagnerness to put down the BBC. Whether Adrian Zenz is a dodgy character or not, the Chinese spkesperson is obviously trying to condemn him and the BBC, in order to assert that the troubles of the Uighar peoople are not happening. you'll notice that the BBC weren't given the opportunity to reply.
Living only a mountain pass journey away, anyone in Bishkek can tell you that the opression in Urumchi is happenening, from the accounts of the refugees who have made their way here. The Chinese are committing genocide, in the same way that they did and continue to do in Tibet, and that is the real issue.