I thought the way he was killed made little to no sense. So he is pretty much invulnerable to any and all attacks because his body instantly adapts a defense... unless you put a bomb in his mouth? Huh?
That IS the point of the strong/unbeatable hero on a team. Get the villain to kick their butts to show how much stronger they are. In this case, kill the unkillable.
Like what they did to Worf in most episodes of TNG.
(Besides, the same thing happened to him in the comics, and he came back from it. If they don't make a sequel, we can just imagine in a year or so he was able to pull himself back together.)