Interesting comments that prompted these thoughts for me:
1. Why wouldn’t you want the abilty to accept attachments?
2. If attachments were disabled for a user how would one deal with the situation when an attachment was sent to one of your Users or a pipleline?
3. Would you expect this contol in an email cleint or server?
4. If a User can or cannot save a an attachment presumabely they can view it to make that decision.
5. Why use HS if your content is so sensitive?
6. Yes, delete really must mean delete.