Seems like there was a general rule among society that you're not supposed to ask SAO survivors about their experience, unless presumably for health/police/etc reasons. Given how Sinon even said, "Are you from /that/ game" and followed it up with "I'm not supposed to ask that, am I?" it implies that the world's trying to ease the survivors of their pain by not making them relive their memories...
Now I doubt the whole internet would happily agree but it's a nice sentiment. lol