I don't see a conflict there:
Delete = Delete
Ban = Ban + Delete (Proposed)
The provision to delete only is already there -- would anyone really want to ban only? What good is a ban without a delete?
I think there are only 2 occasions why a team leader would ban without delete:
1. Because they didn't know the way the system works.
2. Because they are deliberately being vindictive!!
I don't know if there is or not, but there should be a provision to manage your previously banned members anyway just in case you have a change of heart and want to "unban" someone. This would also give you a view of who you had banned.