There's nothing obviously wrong with that code, though it could be improved:
With ActiveDocument.FormFields("Inactive_Reason").DropDown.ListEntries
    .Clear
    .Add "    "
    .Add "Deceased"
End With
If InAcRsn = "" Then InAcRsn = "    "
ActiveDocument.FormFields("Inactive_Reason").Result = InAcRsn