If I was a responsible decision maker in China, wether or not I had something to hide, I would not allow Western journalists free access. The Western press is largely, though not entirely, a mouthpiece of the Western intelligence agencies. Why would anyone allow the presstitutes in ?

China also doesn't allow loads of Western journalists to investigate pretty much anywhere in China, so that can't really be taken as particular evidence that a "genocide" is happening in Xinjiang. Send a journalist to a random factory in Shenzhen and have them start questioning workers about how much they like the CCP and you'll get a similar response.