I would add, however, that training big cats using a treat reward system, while the human is safely on the other side of a fence, is extremely beneficial. The more human-acclimated the animal is, the happier it will be in captivity (ie, less stressed, and much easier to manage).
No hands-on interaction isn't the same as no interaction. Interaction with good barriers is good.
This is true for any large an potentially dangerous animal. If someone owns a reticulated python, they know that they need to have another person present when the cage is open, period--and should always have backup when handling it. But they do need to handle it, because an untamed retic is even more dangerous. Alligators--same deal. Don't put yourself in a position to be mauled and drowned, but if you ever want to move the animal, it's much nicer to be able to have it follow you than to wrestle it to the ground and tape its mouth shut.
It's not a pet, and you shouldn't pet it, but it should see humans as a positive thing--that makes its life far better than it would otherwise be.