He's far more legitimate than this "David Tsoukalos" that shows up on the History Channel's show, "Ancient Aliens" and yet that show gets oodles of funding, massive amounts of viewers, and they don't even try to introduce new concepts or theorize at all.
Calling him a deal old fraud is insanely disrespectful to his memory. He has translated many of the texts, but I'm sure he spent far more time analyzing texts that were already in readable form. I do not see how one could possibly try and call him a fraud - his books are nothing more than his own semi-theoretical take on the subject.
But the fact of the matter is the facts in his books line up. They line up in the biggest of ways by either confirming or strengthening known historical facts.
Nobody says a damned thing when Sumerian accounting documents talking about grain get translated, but when a man translates and theorizes about their religions and the possibility of aliens/gods, he's suddenly a "lying con man"? Last time I checked, he wasn't forcing his books and philosophies upon like the world, like Sigmund Fraud has been pushed upon us for the last hundred years.
Take his books as either insight or toilet paper - but do not sully a good man's memory by calling him a liar and a fraud simply because you do not agree with him.