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.
You being able to move left is covered clearly by the rules under movement speed.
You cannot “do anything unless the rules forbid it”. That’s not how RAW works.
Honestly, RAW just doesn’t work. If you can’t do anything unless specifically allowed, then you can’t do anything because whatever you do will always be more specific than what the rules say. If you can’t do anything unless forbidden, then it doesn’t work because there’s so much the rules didn’t bother with, just leaving it to common sense. And then there’s the fact that sometimes rules contradict. Sure there’s a rule that the more specific rule overrides the general rule, but that’s just yet another contradicting rule on the pile.
There’s nothing specifically saying whether or not you can move left. There’s nothing specifically saying whether or not you can move through walls. We all know you can do one of those but not the other, but it’s not because of anything the book says.
Granted, the book sometimes gives creatures special abilities that let them move through walls, which would be an odd thing to do if it’s something you can do anyway, but the game constantly goes into different levels of detail about things.
I think maybe you’ve missed the whole point of this thread, dawg. I read the first sentence and then dismissed the entirety of your comment because you clearly either don’t understand or aren’t engaging with the premise.