New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  isAdmin: true,
});

templates.application.hbs

{{isAdmin}}

<input type="radio" name="isAdmin" checked=isAdmin onclick={{action (mut isAdmin) true}} />

<input type="radio" name="isAdmin" checked={{not isAdmin}} onclick={{action (mut isAdmin) false}} />

twiddle.json

{
  "version": "0.11.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.10.2",
    "ember-data": "2.11.0",
    "ember-template-compiler": "2.10.2",
    "ember-testing": "2.10.2"
  },
  "addons": {
    "ember-truth-helpers": "1.3"
  }
}