Hi,

I think, with a signed Linux kernel, UEFI Secure Boot can be made to
load any other unsigned Linux kernel, which would imply, any
distribution would be possible to be booted.

How I imagine it can be done:[list]
[*]boot partition would contain a signed Linux kernel which UEFI loads
as soon as the boot sequence starts
[*]the signed kernel would run a simple program that loads a
bootloader like GRUB2
[*]the bootloader would continue as it normally does[/list]