currently I can't add a custom function to a supervise rule. Is there a reason for this?

Background: We have BluePrint managed tickets and actually we have a Supervise rule which should set the ticket to "closed" after 168 hours since the last update and the status "solved". Of course this is not possible if a BluePrint is placed on top of it. Therefore I would have built a custom function which revokes the BluePrint before and then sets the status. Unfortunately I can't create a custom function with Supervice.

Alternatives?

Regards