Interesting theory. Sounds plausible too.
Have you ever had a scared house cat (with front and rear claws) climb up your legs and on to your torso?
I have. House cats are just a smaller and more domesticated version of the big ones - but they behave in very similiar ways.
Yep, That's what made me think that maybe all this tiger needed was something, or someone, to sink it's claws into in order to climb up out of the moat. I know how much it hurts to have a small kitten do this...I can't even begin to imagine the pain of having a 350-pound tiger do it.