There are some concerns with those kind of practices belonging to many levels.

The spiritual philosophy behind them is usually similar to kundalini (for this check the reddit sub, it is very dedicated).

So basically if a master teaches you a secret technique that it can be used to hurt and you end up hurting someone, that master shares a part of the bad karma.

If he teaches a bad man and he doesn't become good, he will withdraw.

If someone only does it for power instead of peace stability and health, same.

Also there are things in those "realms", that can hurt you aswell, and that can end up in bad karma for the master too.

Again it doesn't have to be real (tho i'm inclined to believe so), but that's the belief they carry on with.

Also the consequences for bad karma, for someone "awakened" can be instant, in the sense their own sense of righteousness kind of sabotage their health, or require them to partake in much more meditation or reparation ways, deviating their course in the meantime. So they are extremely cognizant of this sort of thing.

I don't know this Chang reason to do so, but he wouldn't have been the first to withdraw from teaching like that. He might aswell use the training process to determine if someone is worthy to learn more.

There are some concerns with those kind of practices belonging to many levels.

The spiritual philosophy behind them is usually similar to kundalini (for this check the reddit sub, it is very dedicated).

So basically if a master teaches you a secret technique that it can be used to hurt and you end up hurting someone, that master shares a part of the bad karma.

If he teaches a bad man and he doesn't become good, he will withdraw.

If someone only does it for power instead of peace stability and health, same.

Also there are things in those "realms", that can hurt you aswell, and that can end up in bad karma for the master too.

Again it doesn't have to be real (tho i'm inclined to believe so), but that's the belief they carry on with.

Also the consequences for bad karma, for someone "awakened" can be instant, in the sense their own sense of righteousness kind of sabotage their health, or require them to partake in much more meditation or reparation ways, deviating their course in the meantime. So they are extremely cognizant of this sort of thing.