I too not sure about this particular use-case, though found a similar use-case.
As a workaround, you could uncheck the "VOE" field in the pyCaseManagementDefault Work Party rule for the "SupportAssignee" role.
Select the VOE (Visible on Entry) check box to cause the PartyDisplay section for this work party role to appear when the work object entry form first displays. For example, you can require that the originator is automatically displayed. If not selected, the user must select a role from a selection box.
In the above example, SupportAssignee is visible on entry.