Does it really matter whether you agree with Ken Rockwell or not? If he's full of hot air, then your D600 will be fine. If he is right, then dial in his compensation recommendation and... you'll be fine. Either way, you'll be fine.
My first Nikon DSLR (a 2005 D50 that I still use for snapshots) slightly overexposed to my taste in flash mode. So, I always leave flash compensation at -1/3 stop, and everything is fine. That is why compensation controls exist, because we all have a different eye, and are trying to achieve different things.
I actually like and enjoy reading Rockwell's site. But, remember that while he's not the devil, he evaluates EVERYTHING he reviews only based on his own personal tastes and opinions. You either agree with him,...or you're wrong. I am quite certain that his D600 has a green tint right out of the box - compared to what he thinks a right out of the box image should look like. To any of us, the image on his camera might appear exactly as we think it should.