Alternatively, if the worksheet is in a separate workbook that only the team leader should be able to view, you can accomplish this when publishing by removing all but the team leader from the permissions selections.
Tableau permissions are effectively white list, not black list. So that means if you're on the list, you can access that content. If you're not on the list, you will not even see that the content exists. For additional information on permissions, please see:
Hope this helps!