Best not to use the table directly, because even for something as stable as the scheduler the table is an internal implementation detail subject to change.
scheduler.disable() is for workers based on group names, so may not be what you're looking for (affects all tasks that work does).
It appears that queue_task will allow any scheduler_task column to be passed as a keyword argument. Doing that for enabled is probably better than modifying the table directly, or you could make the start time 99 years from now, and immediate=True.
/dps