At first I thought this was a bad idea, mainly because as far as I know JJJ can't see the IP addresses of users on this site and so he wouldn't be able to tell if new referrals were actually fake accounts. But having the guidelines to determine the authenticity of the person invited is a really good idea.
I would go against rating a certain number of stories or getting a certain number of points, as the person on the fake account could rush through games without reading them and leave a rating to up their EXP points rather easily. Also, not everybody posts in the forums - you'll notice many people logon to CYS but only certain members post in the forums, so forum posts would not be a fair way of determining authenticity.
Publishing a story is a good idea as proof is a good idea, I think. It takes time to make a story, and if somebody fakes a referral account and makes a terrible storygame for the EXP points, it'll be deleted and the points taken away from the member who referred the fake account. Maybe it has to be rated at least a 3 on average to be counted? The potential faker would gain more points from publishing the story himself than from creating a fake account and publishing the story, eliminating the appeal of making a fake account in the first place.
Good idea. Unfortunately alexp is unlikely to return to implement ideas any time soon, so this most likely won't come to fruition. Good suggestion, though.