It's an interesting case, that tiger. I hope that man understands how unique she was and doesn't get another tiger with the expectation that he can get the same result. We had a quote hanging at the refuge I worked at that reads "Do not confuse one tame cat with the domestication of an entire species."
Next to that was a picture of KC, our "ambassador" cougar, the only cat that is ever used for pictures, and even then rarely. I have a picture with him, as all interns get at the end of their terms. Still, they would never trust him with a baby like that, and I think it's a bit naive, as sweet as that tiger may have been.
The other anxiety people voice is: "But they are still wild animals; what about their 'wild' instinct? Aren't you afraid they're just going to turn 'wild' (read: 'berserk' - this is another variation of the 'unpredictability' theme)?" The succinct answer is a simple no; what they are calling 'wild instinct' should be more correctly termed 'survival instinct'. It is the instinct to attack prey for survival (food), and only fight to defend one's territory, because fighting is dangerous to one's own survival (evolution has taught even tigers that critical lesson - too bad we humans haven't learned it better as yet),
The idea I get from this is that because she was well-fed, the tiger never felt the need to attack, and that she had no prey drive. But one of the first things the refuge teaches its new interns is to never turn your back on a cage. Cats that have been hand-raised and may otherwise be gentle will
become alert at the sight of a turned back. Because no matter how "tame" that cat may be, it does still have that instinct. Once in a while a staff member would demonstrate the "red light, green light" game to visitors. This involved saying hello to a tiger (who would often chuff a hello back), and watching it. This is "red light." Then the staff member would turn his/her back to the cage. This is "green light." Almost without fail, the "tame" tiger would perk up and go into stalk mode. Sometimes they would start to pounce. "Green light" never lasted long for safety reasons, and the staff member would turn back around into "red light." If pouncing, the cat would stop. If stalking (crouched with ears back), it would relax. Very interesting.
I'm not trying to be a party-pooper, and I'm not an expert, but I think it's scary as all get out that someone can put a child onto a tiger's back and take a picture of it, then justify it with "She's well-loved, well taken care of, and she's never been in a cage." Right, so let me go out and buy a tiger cub, let it sleep in my bed, socialize it, and I'm going to have a 500 lb docile baby on my hands. Cool. No.
Yes, I believe there are special animals who have it in them to... I don't know what... allow themselves to be domesticated? And I believe there are special people that can make it happen. I've always been in awe of Doug Suess and his ability to train grizzly bears and communicate with them so well that he is able to wrestle with them when they're 1,500 lbs, let one put his head in its mouth, and not fear. But even I think even Doug Suess knows not to put a baby on his grizzlys' backs.