... yeah, and if you were a grandmaster out of martial arts flick, and someone was asking to learn the instant-death touch attack that you've never taught anyone else?
Well first off, there is no death touch. I only say that because a great deal of scammers continue to push that myth.
Moving on.
So, couple of things to consider I suppose. Did he seek me out? Did I seek him out? Do I know that he's the chosen one destined to face Baron Von Baron, the evily evilman?
That being said, we will start with the basics.
"So you want to learn death touch eh?"
We will start with the stances of death touch. I will explain why this is important, why it is needed to make the technique work, and other basics. I will correct flaws when seen, explain why the are flaws, and praise proper progress.
Then I suppose, as it is a kung fu flick, I will give reading material on the 9 points of death that one must touch to death touch. Study them in your free time, and learn them well.
Then I will introduce Paralyzing palm. Because you don't always have to death touch. Sometimes it's better to leave them alive for various reason. Also, understanding Paralyzing will better help you understand death touch.
Then, after all that, we learn death touch.
It seems a bizarre assumption to assume that the default is "Well, sure, you're obviously going to get god-like powers, and it's my duty to make sure you do!", as opposed to the default being that, no, you don't get handed the keys to the universe if your mentor doesn't think you're ready, and it's entirely possible they will never think you're ready.
Mentor "Doesn't think you are ready" is stupid horseshit that only serves to pad out a story.
That said, "You can't learn death touch yet because you're too god damn fat, your physicality sucks, and you have no stamina. So you're not ready." is not the same as "Your oneness with those around you and the universe and the universe inside you is not fully ready to be covered in the cosmic microwave...go do pointless shit that I will not help with or explain."
If you aren't able to perform, than I'm going to train you to MAKE you able do perform.
Beyond that, a villain with half a brain could easily tempt the hero over to their side by just being decent to them. "Yeah, here is the training you want. Here's a nice paying job, and all your needs met. Say...why don't we just take this motherfucker over yeah?"
If a martial arts grandmaster tells you he's not going to teach his instant-death touch attack, and he wants you to go sit under a waterfall and contemplate the wind, feels like you go sit under the damn waterfall, contemplate the wind and trust that he has your best interests at heart... or don't and leave. You don't get to be pissy about it, either way.
Then the grandmaster is shit, is wasting your time, and its no surprise when his student either turns evil and destroys all that he cares about, or gets killed by Baron Von Baron of eviltown before he can do anything and now said student is really on the backfoot as he does not have the skills that you didn't bother to teach him....and only the author's ass contains the measures to save you now.
Because sitting under a waterfall, contemplating the wind, and trusting someone refuses to actually tell you anything....is fucking stupid and is a trope that needs to go die.
Also yes you DO get to be pissy about it if...
1. He sought you out as a student.
2. You were sent to him via agreement to learn the things you need to know to stop Baron Von Baron from killing you/everyone.
3. You are his last shot, and without you everything that he has learned, and everything that has come before him to get him to this point, dies with him. Thus wasting the time and lives of everyone who came before him.
I mean, there's a difference between "Everyone's allowed to get a gun in my country, so if someone comes to me asking to be taught, it's my responsibility to make sure they learn how to shoot a gun responsibility and safely" and "This person asked if I'd teach them how to make a nuclear bomb".
No. It's more like "This person asked me/I ask them to be my student, to teach them the knowledge that COULD allow them to make a nuclear bomb." But instead I chose to fuck around, piss them off, fuck around, waste their time, fuck around, piss them off, waste more time, fuck around a little bit more, waste some more time, piss them off even further and suddenly HOLY FUCK, THEY WENT AND LEARNED HOW TO MAKE A NUCLEAR BOMB BEHIND MY BACK AND NOW THEY WANT TO DETONATE IT JUST TO HURT ME!!
Ah shit...who could have seen that coming?
Because fictional mentors are NOT real teachers, written by people who don't actually give a fuck about the process, nor do they understand it. So instead, they'll pull some stupid shit out of their ass later down the line to give their hero the skills/power that you should have done in the first place Mentor.
Then, after that, hundreds upon hundreds upon hundreds of fanfics will be written around the premise of "Why didn't he just teach him death touch?"