Comment 12 for bug 1619188

I think unattended upgrades should be disabled by default on the live media since there isn't space for upgrades when the Ubuntu live images is run 1) from a DVD or 2) from the no-persistence that recent versions of usb-creator-gtk unconditionally uses or 3) as written by dd. I believe it's similarly inappropriate even to notify about potential updates even security ones in this environment.

sudodus, if you're interested in trying to submit a patch for this, look at the scripts/casper-bottom/ directory (in the casper source) which is where these kinds of customizations of the live environment are made.