Bear with me here. Said in different tones by and about different people, this could be a big red flag... but this was a special case and it got me thinking. Just speculation coming up, a possible way of looking at the world and training.
There are students and teachers. That can be a job description or a personality type. Either can be limitless horizons or can lock you in a box. In martial arts, it is far more likely to lock you in a box.
It doesn't have to be this way. I'm pretty sure it's not supposed to be this way, but it seems to wind up here far more often.
In martial arts, the student personality is weirdly passive. They train, which is good. Some follow fads and some latch onto instructors and follow them, but in either case following is the operant word. They collect techniques, they worry about moving right and when they get under pressure or get tested, they try to do what sensei would approve, not necessarily what would work.
If your hackles go up and you say, "Not me" or think that I am painting with too broad a brush, think about this: I've spent more study hours in martial arts than I would need for an MD. Far more than I would need for a business degree. The people who get MDs and business degrees spend countless hours studying real disease and real business. Outside of cops, in all the seminars this year when I asked if anyone had spent a single day in their years of martial arts training studying how real criminals really attack, one hand went up. One.
Memorizing assault statistics (the percentage of rapes conducted by strangers; robberies in daylight versus dark) is not research. It is trivia. They call it trivia for a reason, it is trivial. How an attacker holds a knife, range and terrain considerations, developing distance with or prior to assault...
So students follow a lead and in too many the parts of the brain that should be going, "This doesn't make sense, if I was a bad guy I would never attack this way," somehow turns off, and martial training in its way becomes as mentally passive as watching television.
And there are teachers. Some people start martial arts from their first day in teacher mode. They want to understand and explain. That's good. It's very good, usually. (Some do it for ego. They want to be in a place where people call them 'master' or some other silly title.) But most do it for love...and like many people that love a thing, they don't want it banged up. In a physical object that makes sense, sometimes. You don't want to break a Faberge egg.
On the other hand, martial arts should be about as far as you can get from a Faberge egg and you can't really understand something without taking it apart. Much less something physical and visceral and about conflict and contention... you can't understand it to any depth without road-testing.
But to this particular teacher personality, being sure is the hallmark of a good teacher and any test risks doubt seeping in...
That creates a need for a critical third type in martial arts. The explorer. This is what the instructor mentioned above sees in my friend. Toby will listen, he will learn and absorb...and then he will test it. Sometimes at great personal risk, sometimes just with common sense and doubt. The skills he picks up will not just be learned-- they will be put in situations where they will succeed or fail or expand. (That is a huge problem with preserving arts: sometimes in the road test you find out not that they were less than you feared but they were bigger than you imagined, and that means that you never understood them at all. Humbling.)
Toby's teacher, like many extraordinary (as opposed to merely good) teachers, spent most of his training life as an explorer. Not just learning everything he could, but risking and testing and sometimes failing. What comes out of failure is often more compact, useful and truer than what went in.
So he sees Toby and he shares more, because the student and teacher personalities don't get it. They don't understand the awesome power and freedom of doubt. They think that training is about answers and proficiency and safety, and the explorers see it as about clarity. Answers are dependent on questions. Proficiency can (read "Deep Survival") hamper adaptability. In a world with a 100% death rate safety is and always has been a complete illusion.
The explorers get a lot of shit, but they are the ones who will carry a living thing into the next generation.