I didn't see anything about completely disabling automatic updates there. Closest I could find was:

"After a refresh, the next refresh can be delayed by up to 60 days, after which a refresh will be performed regardless of the refresh.hold value."

With windows update the trick since MS enforced a similar update policy is to change the user the Windows Update service runs under to an account that doest have the required permissions.

Not sure if that would work with Ubuntu though ;)

i am surprised that this is possible under windows. for ubuntu, it should be possible to disable the daemon that runs the update checks. at worst by hacking a script where the process is started.

There's a solution you're not seeing https://ubuntu-mate.community/t/how-to-completely-remove-sna...