Hello,
If the user is a part of the group being sent notifications then there is no way to exclude them as long as they are still in the group. In many cases (such as the workflow supervisors), the entire reason to be in the group is for the notifications so it may just may sense to update the operator account and remove them from the group entirely.
If you want to submit an enhancement request to be reviewed for a potential future release, please feel free to contact Campaign Support.
Regards,
Craig