But that's wrong behaviour and a bug IMO @ljm42 update_cron should be run regardless if user shares are enabled or not. The mover script should be intelligent enough to figure out that user shares are not enabled.
update_cron is an integral part of the OS, and many plugins rely upon it. User Scripts, Parity Check Tuning, SSD Trim, CA, FCP etc etc. None of those require user shares to be enabled.
It isn't mover related per se, but rather scans all .cron files within /config/plugins and adds them in unless the system runs in safe mode.