Here is an example of someone being put forward as an authority when they do not have any expertise in this particular field.
"David Frawley is one of the few Westerners ever recognized in India as a Bedacharya or teacher of the ancient wisdom. His work in this book reflect this tradition and his contact with numerous Vedic scholars."
The reference to his being one of the "few" westeners ever recognised in India as a teacher of "ancient wisdom" is a dubious one. Virtually anyone can gain recognition of sorts in a country the size of India. As is pointed out in the book review, Hinduism and yoga has a fairly anarchic structure in India. There is no universally accepted authority by which David Frawley can be "recognised" as an expert.
Whatever he may or may not know about yoga in general, his knowledge of the Kriya tradition seems to be limited. Most of whats written in the review seems to be a rehash of claims made by Ananda/J.D.Walters for a number of years. I doubt that David Frawley has any first hand knowledge of the situation.
He is entitled to write his opinions in a book review, but they should be seen for what they are. One persons opinions, based on the little that he has read about the issues. He probably knows far less about this particular matter than most people reading at this board.