Apple's news aggregation app News and its Beats 1 radio station had worked fine in Hong Kong, where he began his trip and where there is basically no internet censorship, but became unavailable as he entered mainland China, where the internet most definitely is censored.
The recently-launched News app was first made available on devices registered in the United States, but the service has been available to use around the world if users make sure their device's region is still set to the US. Salibra, a Hong Kong-based founder of bug software testing platform Pay4Bugs, was the first person to widely publicise the fact that this is not the case in mainland China, posting a blog about the ordeal. It quickly became a PR thorn poking into Apple.
By testing the availability of News in various areas and on different phone networks he worked out that the service was only blocked when connected to mainland China networks. His detailed tests were outlined at Larrysalibra.com, but the long and short of it was that Apple seemed to have added a "kill switch" for News and Beats 1 in China. ("Music is subversive", Salibra drily noted).