Did you know that the sea level has changed in the past 4,000 years? Guess what that means? The altitude today is not the altitude when the pyramid was constructed. Altitude is determined according to sea level or some other marker. The starting reference point and endig reference point are both missing from the author's work.
Actually, sea level has nothing to do with the altitude of the pyramid. It is basically the measurement of the base to the top. Not from sea level.
Also when you ask which mile, what would you say if someone asked you how many miles away the nearest gas station was? Would you give them the distance in Norwegian miles? That would be highly misleading to the person asking, who in all likelihood is expecting you to give an answer in reference to the mile in it's accepted standard. If you saw my earlier post, if there were other entities responsible for establishing this standard and also for building the structures, it wouldn't be too hard to fathom.
Anyways, the arguments you are bringing up are nowhere near the point of discussion within that book. Many books have been written on the measurements of the pyramids and you can google many websites on the pyramids of Giza and see that the data presented here is not unique to this book. These are well researched facts that have been around for a long time. If all of this is new to you, I suggest you look into it a bit.
The reason the construction of the pyramids has anything to do with the Nephilim is because of the fact that there is much evidence that proves that they, along with their b'nai ha elohim fathers (fallen angels) were the ones that built these structures. There is a reason why they built these and they are not there merely for decoration. It has a lot to do with the Apocalypse mentioned in the book of Revelation.
The Nephilim story in Genesis 6 is much more than fairy tale. It is more relevant in today's world than any of us can even imagine.
