Interesting, I remember him always posting about using slurry, maybe that message to you was from before he was taught by the barber. Here's a link from his site, plain water honing isn't mentioned, only adding a few drops of water to the slurry to thin it.

Honing on Japanese Naturals | Eastern Smooth: The Blog

Personally, I've found that some JNat stones produce a better shaving edge with slurry and some produce a better shaving edge with water. One just needs to experiment to see what works better with each individual stone.