An unsubstantiated statement is simply a guess.
Now this is not a guess ~ the zoo had a responsibility to make sure the animals could not readily escape.
You are so right.
I do not understand those who switch responsibility for the escape from the zoo to those who got chewed on.
“Taunting” the tiger might make give her more incentive to get at them. This is irrelevant to the prime issue: The zoo’s responsibility is to keep the animals away from the customers no matter how badly the animals want out.
If the guys in question behaved badly, they should be punished appropriately, but it doesn’t mitigate the zoo’s screwup in the least.