Nope. Still not logical enough for Kain to disintegrate the very same moment he touches water. And do not forget he's not a regular vampire- he's the king of vampires. That was nothing more than the game's excuse to make its platforming a bit harder.
Just because you're king, doesn't mean you're all powerful. I don't see the lack of logic in it, for the most part. Though I do believe, it's excessive that he instantly dies. I'd have thought he would be able to last a bit before then.
What fails in that game is not that Kain dies in water, it's that he takes like 20 slashes to kill an enemy... a human enemy, when the sword AND him, are suppose to be so powerful.
Lets just assume it was all anointed holy water spilled from the heavens
In Legacy of Kain, Cursed Vampires are vulnerable to all water. Raziel still has it after he becomes the Reaver of Souls. It's only by getting his brother's soul that evolved into one that can withstand water, that he is able to travel through water.