There is a lot to read there and figure out, but basically what it is saying is:
If you are severely de-hydrated and then you drink water then it will cause your brain to swell and to die.
I need to go through it and pm some of the people to properly figure it all out, but if someone on here wants to do it before me then they are welcome.
The advice is to drink an electrolyte/re-hydration solution very slowly for a few hours.
I think that is a good idea no matter how de-hydrated you are.