Author here. Yep, I don't want to force a particular bootloader on anyone. The bootloader is a piece of software owned by the system administrator, not necessarily by any of the several operating systems installed side by side. If I force a bootloader on the user, that makes dual boot configuration harder, and it's important to allow that. I happen to follow GRUB's multiboot specification, which has the advantage that a lot of bootloaders implement it. It's not perfect though and I'll probably invent and adopt my own bootloader protocol in the future, but the sysadmin's choice of bootloader continues to be important on my mind.