Update "automaticaly install security updates"


Before I allow this update can you please enlighten me why an informed hacker can not through this channel apply their own 'tweaks' without my knowledge?
I know nothing of the Ubuntu core but I notice that a 'systemd' reloads something from a system dump [journeld - I think] which seems to defeat a reload by me of my backup of an earlier system backup???
Just my concerns as a user. [Ubuntu Mate 18.04]