I know people that lived in Xinjiang for most of their lives. The Uygurs there can be extremely violent. This includes car bombs, murder, and armed attacks. One of the people I know personally witnessed armed Uygur hiding behind pregnant women as they attacked a government building.
Your [acquaintances'] personal experience with the region and its people is much more credible than the idea that simply because people are nominal Muslims, they must be hunted down and killed.
People in Belfast say similar things about "The Protestants" but that doesn't mean that all Protestants are terrorists.