SOLVED.
I'm now happily running an encrypted netinstall (with /boot encrypted)
without having to worry about AMT/ME, even if this machine isn't running
Libreboot.
What I did to finally be able to boot automatically:
I removed "quiet splash $vt_handoff" from the grub bot config ("c" when in
grub).
This worked. I tried again only removing splash this time.
It worked also.
So after booting, I removed quiet splash altogether (I don't like the black
screen "quiet" offers).
And did an "update-grub".
Worked marvelously.
