"Expert" is a relative term. He may not know all the intricate details. But having to live in the system he has first-hand knowledge, and not being part of the system (apparently) he has no personal reason to hide its dirty secrets. Also, his experience is likely to be typical for other people like him. This, I would say, makes him a great source. Then if an "expert" wants to perform a scientific study or in-depth journalistic investigation or some other thing "experts" are supposed to do, the said expert would need to contact him and other like him, for knowledge. Which he, thankfully, has freely shared with us here.
