

Disabling su is stupid because you always need some form of privilege escalation, restricting sudo to apt offers no security benefit whatsoever as apt allows arbitrary file modification, disabling root ssh provides no benefit when the unprivileged user has sudo access – I could go on.
Well, they have – I think. When you download an edited image, it supposedly downloads an image with edits applied. The original is optionally available too.
If you download the edited image, this is effectively equivalent to the status quo of image editing.