As i am able to see in my instance, IncidentStateSNC SI is read only based on protection policy. 

and below is the actual code in the SI.

var IncidentStateSNC = Class.create();

IncidentStateSNC.NEW = "1";
IncidentStateSNC.IN_PROGRESS = "2";
IncidentStateSNC.ACTIVE = IncidentStateSNC.IN_PROGRESS;
IncidentStateSNC.ON_HOLD = "3";
IncidentStateSNC.AWAITING_PROBLEM = IncidentStateSNC.ON_HOLD;
IncidentStateSNC.AWAITING_USER_INFO = IncidentStateSNC.ON_HOLD;
IncidentStateSNC.AWAITING_EVIDENCE = IncidentStateSNC.ON_HOLD;
IncidentStateSNC.RESOLVED = "6";
IncidentStateSNC.CLOSED = "7";
IncidentStateSNC.CANCELED = "8";

IncidentStateSNC.prototype = {
initialize: function() {
},

type: 'IncidentStateSNC'
};

if you can update the SI then it is good. else update the BR condition accordingly.

Thanks,

Ali