I don't think it matters. All the seller needs to do is go to http://www.icloud.com/find (on an actual computer) and remove the device from his account. The OP reboots the iPhone and it's now his.
Yes, Apple's instructions say what to do if the phone has been restored. It still works, just not through the iOS app. Now he has to use a computer.
But I have no reason to believe that he will actually do that. I mean, he's telling me that he just got back into the country today (though he was in New Orleans just four days ago) and is leaving the country tomorrow. Who does that? Why would anyone fly all the way back to the US just to turn around and fly abroad again the very next day? Everything he says stretches the limits of belief.