You're right, those quotes were from study of people already in RF, but they make a point of how high protien intake CAN cause renal damage.
But (and thank you, Java) someone has pointed out that :
"Now, there certainly is an amount of protein that will cause damage to the body just like anything we ingest, including water."
That's basically the point I was trying to make, until someone went postal on me
And finally, to point out again, my example was for a "A 150(pound) bean pole that didn't work out would be in renal failure in no time.". Not a bodybuilder, a regular joe-off-the-street.
It's all relative to what you need. What your body doesn't, it gets rid of, via the sewer system, part being the kidneys. Overload the system over time, and something will give, someday.