For what it's worth, the message I get from the original quote in hindsight, is maybe coming from a different but related angle. I think he was talking about something that most people go through when they are starting out and become extremely enthusiastic. You know those days when you thought everything your instructor said or taught you was the ultimate secret that could solve everything, and only the people in your dojo had this knowledge? How about all the instructors and black belts in different arts who have explained to you that (insert style or technique, etc.) is garbage, and we have the real stuff. One good way to find out about that is to learn from different people and have them cancel each other out.
I think he was just warning me to leave the training in the dojo when I walk out the door. Remember learning bunkai and thinking that was the only answer to some sterile situation? He observed the class and that the training was excellent. He remarked that the advanced students were extremely tough and focussed. But I think everyone has to get to the point where you put your mind, body and spirit into the training and let it become part of you, without trying to make reality fit whatever you have been practicing.
For example, If i sit and stare at a candle for a while, I could say that it helps me to relax my mind, let go of interfering thoughts and practice being aware of what's going on in the present. If I then go out the door and cross the street, I don't want to be thinking about the candle, or close my eyes and pay attention to my breathing.
It's like the whole technique thing, or different types of drills. They serve a real purpose but they become a danger and a liability if one becomes attached and stuck on them. Anyway, that's what I get from "Learn everything you can, and then forget it".