Special Abilites of Trolls

[david]

When I testing my mansion earlier, I made a trap in which you had to walk a troll over many moving platforms, which would descend down into water. However my puzzle did not work correctly, as he did not die when sunk into the water. After conducting a few tests I discovered that he did not die when on a moving platform that descended into the water as long as he DID NOT MOVE. Has anyone else discovered this? Or is it just a glitch?

P.S. Heres a video of the situation