also, it's actually mostly fine to boot from a compromised disk as long as every resource involved is properly authenticated. Of course, the less you boot the better, but again when resetting the disks like this we do this from the initrd, i.e. from the signed, vendor-supplied UKI in a short-lived environment, not from the rootfs that might be user (and thus attacker) controlled.
But I think ultimately we can just agree to disagree on the security model, no?