This lemon juice cleanse came after the orange juice cleanses and much more complicated, yet quite simple also. the author probably wanted to be differant. There was also a famous French Clay doctor that used lemons, but again, his method was a simple one.
Either way as long as you keep it simple, it will work. I noticed in the pdf you sent, it appeared it was made as a way for a manufacturer to sell a product, if you use such products, you always want to know if they are simple herbs/foods and not a synthetic vitamin supplement.