Kendo UI Grid conditionally prevent editing

HTML

<link rel="stylesheet" href="http://cdn.kendostatic.com/2014.1.318/styles/kendo.common.min.css">
<link rel="stylesheet" href="http://cdn.kendostatic.com/2014.1.318/styles/kendo.default.min.css">
<script src="http://cdn.kendostatic.com/2014.1.318/js/jquery.min.js"></script>
<script src="http://cdn.kendostatic.com/2014.1.318/js/kendo.all.min.js"></script>
<div>Chai cannot be renamed</div>
<div id='grid'></div>

JavaScript

var oEditCell = kendo.ui.Grid.fn.editCell;
var oInit = kendo.ui.Grid.fn.init;
kendo.ui.Grid = kendo.ui.Grid.extend({
    init: function () {
        oInit.apply(this, arguments);
        if (typeof this.options.beforeEdit === "function") {
            this.bind("beforeEdit", this.options.beforeEdit.bind(this));
        }
    },
    editCell: function (cell) {
        var that = this,
            cell = $(cell),
            column = that.columns[that.cellIndex(cell)],
            model = that._modelForContainer(cell),
            event = {
                container: cell,
                model: model
            };

        if (model && this.trigger("beforeEdit", event)) {
            // don't edit if prevented in beforeEdit
            if (event.isDefaultPrevented()) return;
        }

        oEditCell.call(this, cell);
    }
});
kendo.ui.plugin(kendo.ui.Grid);

var products = [{
    ProductID: 1,
    ProductName: "Chai",
    SupplierID: 1,
    CategoryID: 1,
    QuantityPerUnit: "10 boxes x 20 bags",
    UnitPrice: 18.0000,
    UnitsInStock: 39,
    UnitsOnOrder: 0,
    ReorderLevel: 10,
    Discontinued: false,
    Category: {
        CategoryID: 1,
        CategoryName: "Beverages",
        Description: "Soft drinks, coffees, teas, beers, and ales"
    }
}, {
    ProductID: 2,
    ProductName: "Chang",
    SupplierID: 1,
    CategoryID: 1,
    QuantityPerUnit: "24 - 12 oz bottles",
    UnitPrice: 19.0000,
    UnitsInStock: 17,
    UnitsOnOrder: 40,
    ReorderLevel: 25,
    Discontinued: false,
    Category: {
        CategoryID: 1,
        CategoryName: "Beverages",
        Description: "Soft drinks, coffees, teas, beers, and ales"
    }
}, {
    ProductID: 3,
    ProductName: "Aniseed Syrup",
    SupplierID: 1,
    CategoryID: 2,
    QuantityPerUnit: "12 - 550 ml bottles",
    UnitPrice: 10.0000,
    UnitsInStock: 13,
    UnitsOnOrder: 70,
    ReorderLevel: 25,
    Discontinued: false,
    Category: {
        CategoryID: 2,
        CategoryName:...