Angular: Strange True False Binding to List

http://angularjs.org/

HTML

<script src="http://code.angularjs.org/angular-1.0.1.js"></script>
<link rel="stylesheet" href="http://twitter.github.com/bootstrap/assets/css/bootstrap.css">
<form name="myForm" novalidate ng-controller="MyCtrl">
    <div class="control-group" ng-class="{'error': myForm.parameter.$error['required']}">
        <label class="control-label" for="title">Test - {{myModel}}</label>
        <div class="controls">
            <select name="parameter" ng-required="!(myModel == true || myModel == false)" ng-model="myModel" ng-options="x.value as x.label for x in trueFalseOptions">
                <option value=""></option>
            </select>
        </div>
        <div ng-show="myForm.$error['required']" class="help-inline">Missing input. {{myForm.$error}}</div>
    </div>
</form>

JavaScript

var myApp = angular.module('myApp', []);

//myApp.directive('myDirective', function() {});
//myApp.factory('myService', function() {});

function MyCtrl($scope) {

    $scope.myModel = null;

    $scope.trueFalseOptions = [{
        value: true,
        label: 'Yes'
    }, {
        value: false,
        label: 'No'
    }];

}