Transactional Role and Inquiry Role Assigned to User - Different BUs

Summary

How to allow inquiry only for one BU and transactions for another BU for the same user and the same module/work area

Content

I thought of this use case today and I'm interested in what others think:

Say you want your user to create AP invoices for BU1, but also have inquiry-only rights to AP invoices for BU2. So you create a custom AP transactional role and a custom AP inquiry-only role. You assign both roles to the user, and assign data access of BU1 for the transactional role and BU2 for the inquiry role. My hypothesis is that the user will be able to transact for both BU1 and BU2, given that the DSP action you need is "Manage Payables Invoice"; there is no DSP action of "View" or "Maintain" for AP invoices. Most of AP and receivables is like this.