Comment 2 for bug 2016894

Have you tried setting the --unrestricted option on the submenu?

In any case, modifications to grub.d scripts are outside the normal operation of the grub2 package. It's very hard to merge them on updates, and you really shouldn't be touching them. I think it's a mistake they're in /etc.

If you want support for grub superuser password stuff and unrestricted default class, I suggest submitting patches to upstream that enables setting those from /etc/default/grub, as I don't foresee this in scope for the Ubuntu enablement work, and the same applies to enabling the features to work if they're not even supported by the generator.