Bypassing disk encryption on systems with automatic TPM2 unlock

This is mitigated if your initramfs + kernel are measured into the TPM, right?

Edit: never mind, I think it's still vulnerable.

Your edit is correct. The kernel and initramfs are exploited unmodified to boot a tampered root filesystem, which allows userspace tools to extract data from the TPM, as the PCRs used to protect data like the LUKS passphrase have not changed.