To me this appears more to do with portal system settings.
Try integrating a test demo WDA application in an iView, embed it in an portal role and test if you launch the application.
Another option is that SAP delivers NWBC role for MSS as well.
You can view the role in PFCG transaction SAP_MANAGER_MSS_SR_NWBC_3. Try assigning it a user and check if you are able to view the applications.
Hope this helps.
Regards,
Sahir.