From some recent posts here and your post, I believe what is somewhat confusing is..
"...a command line tool to install to pen drive, USB hard disk drive, USB zip, or USB ext..."
Some are interpreting this as an installation to USB hard drives, or the old USB-ZIP drives.
When in fact the script installs to pendrives and supports USB BIOS Boot options of USB-ZIP and USB-HDD, both of which are fat based. It also supports USB EXT which is native Linux ext2 based.
I have sent this message to Distro Watch for correction.