You don't really need evidence, you just read between lines - Chinese gov would use any opportunity to blame US company for the crash and since they kept quiet

You don't really need evidence, you just read between lines - Chinese gov would use any opportunity to blame US company for the crash and since they kept quiet it's pretty clear it was human error/action. And considering HOW the airplane crashed it's pretty clear it was intentional, you need to try really hard to crash straight down vertically (with intact airplane).