Installing GoboLinux

I'm attempting to get a working Gobo system for about the 10th time. I'm
installing into a VBox virtual machine.

Lucas recommends "Full" v. "Typical", so I tried it. This is a stream of
consciousness record of the result. If this sort of thing irritates you,
kindly avoid/ignore this thread. Thank you.

Part 1, When I format the (virtual) hard disk as part of the install,
installing grub apparently is required because the resulting installed
OS will not run without it. Question: If grub is required, why am I even
given the option to not install it?
Note that I know what grub is, so you don't need to explain it. And I
also know I can later install other OSes that are selected via grub
(though in a VM, that's rather silly). But can't the installer look at
the hard drive to determine whether grub is already there so to better
handle the situation? Is that asking too much of the "friendly" Linux
operating system?