I'm expecting the system time and date to be 1970 something or something random, but it is the true date and time to within a few ms of atomic time. Disabling in Dietpi-config has no effect.

I have set Time sync mode : Disabled in dietpi-config > advanced
I have removed fake-hwclock and removed hwclock.sh links from rc0.d, rc6.d and rcS.d
I think that it is something in the bowels of systemd in dbus-org.freedesktop.timedate1.service that is syncing the time with network time.
I have installed a rtc ds3231 and want to have the system time set from that *only* regardless of whether there is an internet connection. And I don't want the system clock to be written to the hwclock behind my back! In the rc.local script I will have a line hwclock -s to set the syst clock from the hwclock.
I need to sync the rpi with other timing equipment and therefore don't want it to sync with network time across boots.
What is the best way to stop the rpi from syncing with network time?
Thanks,
Gordon Williams