Comment by Guvante

You need to only have the ability to execute code after the hibernation not before and the machine needs to be permanently unavailable to the user after.

As I said quite rare situations.

If you can read this kind of data you have the ability to run code which means you already owned the entire operating system making capturing the key next entry beyond trivial.

You don't need to spoof anything, we assume here you can read the key from RAM remember.

If you could execute code before hibernation you similarly already had the key.