Please fix desktop security issue in upgrade process

The upgrade process, from Ubuntu v18.10 to v19.04 at least, exhibited rather awkward behavior that creates a security issue for anyone unable to put their Linux desktop computer in a vault connected to an electric outlet, throughout the course of the entire upgrade progress.

This is because the upgrade system disables the lock screen. Now, I am not sure why Canonical thought it was necessary to do this in the first place, but let's just accept that the lock screen interferes with the upgrade process somehow. In that case, it would be more secure to complete the remainder of the upgrade as a boot splash, so that the user is not logged in and wide open to interference.

This really bites in a college setting, for example, where it is impractical to trust your roommates--notorious pranksters--to leave the computer alone for potentially hours, while the upgrade completes. Please either find a way to let the lock screen operate normally for the whole upgrade duration, or else move the instructions to a boot time context where no desktop user is logged in.