I don't know about you, but once I have a minimal working kernel or a coreboot fallback, I never really update them. So having no way to recover them without hardware intervention is fine. The kernel I may recompile, patch, etc would be somewhere else.
The job of this minimal kernel and initrd would just be to kexec the other kernel, and let you recover coreboot if needed.
It really, really happens in many environments that you find you need to update that kernel.
It's true that you, personally, might not want to do that. But any realistic design needs to accommodate a kernel update, which further means any realistic design needs to accommodate two kernels. Because, sooner or later, you'll flash a broken kernel (I did this once on 1000 nodes) and you have got to have a way out.
Not saying you *have to use that*, mind you; but a design has to be able to do that.
ron