Guardian Cross and old devices

I was preparing to send my iPhone 5 in for a replacement as it has the battery issue and I wanted to make sure the phone was clear of app data. I was checking out Guardian Cross in particular as it was mentioned to be locked to a device. To my surprise, a newly restored and re-setup iPhone with a re-downloaded Guardian Cross does not load up any game save automatically; you are required to login or start a new game. This is good news for people who wants to trade in or sell their old iDevices. Do check it out yourselves to make sure, just in case...