Can a spirit become "completely disarranged without possibility of re -integration"?

[Patrick]

But in the perspective that if a normal being dies, it will get re-born and if a ego dies, it will realize "Nirvana", what then will happen to a spirit that gets destroyed? And why is this undesireable?

The illusory perspective of the Creator that we are would be dispelled and so one would find itself back being the Creator once again without illusions. Your point of view would simply shift back to being the One Infinite Creator.

So the Creator looses the opportunity to fully explore the creation from the unique point of view that you are.