Where does that webpage say that he is not a Mormon?
One of his books on Amazon:
“MORMONISM. The Faith of the Twenty-first Century. Volume 1”
https://www.amazon.com/MORMONISM-Faith-Twenty-first-Century-1/dp/1894161009/
“Edward K. Watson lives close to Vancouver Canada. He is married to Eppie Lida and they have three sons, Edward Ryan III, Daniel Kenneth and Justin Amadeus. He is an active member of the Church of Jesus Christ of Latter-day Saints and served a voluntary two-year church mission to the Philippines. He uses the most advanced Bible-study aids in existence and has put in over 30,000 hours researching and writing about Mormonism and biblical studies which is compiled in the eight-volume MORMONISM Series.”