If I have understood correctly BackupMenu v2 use a ramdisk.
So it starts in rootFS, it creates a ramdisk and it copies some libs and other files to ramdisk, then it switches to ramdisk (and it dismounts rootFS).

Why don't materialize this ramdrive and then boot with initrd ?

• Faster start-up
• Possibility to use other boot system (i.e. multiboot, u-boot)
• Possibility to run BackupMenu even with rootFS destroyed. I.e. u-boot bootloader which loads a kernel and a initrd (containing BackupMenu) from SD Card
• Possibility to have many versions of Backup menu installed (many different initrd files)