My main fear was that he had tested it with bad data and adjusted it down to ph4. Now we can find out.
The other thing is that if it was strait water even so far out it is not the end of the world. Water due to its limited count of +- ions that can actually move around can not actually gank pH in soil very far. A nute mix with salt at ph10 is way different than a gallon of water at ph10.
Most older experience growers do not worry about water pH until nutes are added. I check it because it gets you in the habit and an extended vacation for pH equipment can cause issues if not stored properly.