I know because, as I stated, I also happen to know who is being discussed. Xue might be private, but the person being discussed and accused of being a fraud is NOT as private. He used to be quite active on here a few years back.
Also, NY might not have mentioned names, but he made it pretty clear he was talking about someone who said he had been offered the chance to teach a full-year course at an upstate NY college, but they wanted a certificate that gave him permission to teach. He could not produce one because the place where he trains just doesn't issue them.
Having said all that, I know the person in question, and he is adamant about NOT being identified as a Sifu. NY is partially right in that he was not certified to teach. However, he was given PERMISSION to teach. NY says he "knows this person's instructor." I guarantee you: he means the person's OLD instructor.
Look at it this way: if you are training at Wing Chun School #1, but then you move away and have to start going to Wing Chun School #2 in order to keep training, then why would you need to be certified to teach by Wing Chun School #? You don't train there anymore! And I doubt school #2 would call school #1 and say, "I want to certify this guy to teach. What do you think?" No, sir. The new school wouldn't contact the old one to get "permission" like that.
I don't know what NY's problem is, because the person in question is someone I have known for a while and talk to regularly. I know that, aside from an email they sent to NY last summer where they apologized for how their relationship went sideways, the unnamed person hasn't even THOUGHT about NY for the last two years. Meanwhile, NY is on this site, bashing away and griping about someone who never even utters his name.
Sad, really.
As for fraudbusting, I am not sure what your rules are about that. Since the person is not named, but it is made pretty clear who NY means by the way he describes their "credentials" thread, I think it would be worth looking at. Then again, it's your site, so what do I know?