Looks like we only install grub (legacy) if we're about to install grub-pc and "grub-installer/grub2_instead_of_grub_legacy" is preseeded to false, which typically doesn't happen. It's default is true, and we don't set this in ubiquity or d-i.
grub-legacy-ec2 installs some data for EC2 instances that is relevant to grub; we should definitely look at how we'd affect it by removing grub (but I think it's safe there)
The open question that remains is handling upgrades.
Looks like we only install grub (legacy) if we're about to install grub-pc and "grub-installer /grub2_ instead_ of_grub_ legacy" is preseeded to false, which typically doesn't happen. It's default is true, and we don't set this in ubiquity or d-i.
grub-legacy-ec2 installs some data for EC2 instances that is relevant to grub; we should definitely look at how we'd affect it by removing grub (but I think it's safe there)
The open question that remains is handling upgrades.