Disclaimer: this is purposefully obtuse.
Other effects in the game which explicitly state they kill you:
Shadows, succubi, massive damage, death saving throws, beholder death ray (notably not even their disintegration ray kills you), power word kill, vampires, mind flayers, night hags, drow inquisitors.
Clearly, if they intended for disintegration to kill you, they’d have said so. Since specific overrides general, and there is no general rule that disintegrated creatures are dead, I rest my case. QED.
I don’t need to point to where RAW says that I cannot play it because nothing leads one to believe that you can’t. If your character is polymorphed, its state changes but you can still play it.
Where does it say that, RAW? I’m using your own logic against you. You’ll have to come up with a better response than that.
Edit: to clarify, where does it say RAW that you get to continue playing when polymorphed into a non-playable character?