I would say what you did is to "neutralize" the ME firmware part in the flash BIOS. But this is only firmware that the ME loads additionally to load applications like e.g. AMT.
The ME has it's own internal ROM containing it's very own firmware which is inaccessible and can not be modified.
So what you have is libreboot running on top of a still functional IME. All you gained is, that you got your BIOS of choice installed, and to remove some ME apps from the flash image. Correct me if I am wrong.
This is why I run libreboot and I neutralized the IME by flashing my BIOS using SOIC-8 chip clips and a Bus Pirate.
I guess I'm paranoid.