Note that this wasn't so much about figuring out how to disable Intel ME, which is accomplished by sending an HECI (Host Embedded Controller Interface) command in the same way it has been for ages.
Rather, this was about fixing a buffer management bug in Coreboot which prevented S3 sleep from working with secure boot enabled (basically, coreboot would clobber itself with the TPM log on wake). This bug required System76 to switch to S0ix suspend and in turn, the ME to be re-enabled (as the ME manages some peripherals in S0ix sleep).
Rather, this was about fixing a buffer management bug in Coreboot which prevented S3 sleep from working with secure boot enabled (basically, coreboot would clobber itself with the TPM log on wake). This bug required System76 to switch to S0ix suspend and in turn, the ME to be re-enabled (as the ME manages some peripherals in S0ix sleep).