hmmm, tricky tricky.
First of all, the website does exist, see
http://nflbettingsystem.com/gregsgamblingsystem.com/ so I wouldn't be too quick assuming it's just a troll.
Secondly, it could be that they have written about it in a book, it could not be as well - I don't know how to check though since looking at the copyright number (TXu - 1-583-740) he gives, the u after the TX indicates the registered work is unpublished.
Finally, whether a system could be registered... well, that seems rather tricky for while seperate ideas can't be copyrighted (a story about a vacation), the creative works itself can (YOUR story about a vacation). So I think (being a simple layman) the outcomes of the system can't be copyrighted while the system itself might. In that case legally there probably aren't any problems if you publish the same picks without mentioning or pointing to something similar to the system as it will probably be very hard if not impossible for that to prove you didn't just come up with the exact same picks by throwing darts to the list.
Either way, never had any Law or similar so don't take my word for it -- but I wouldn't immediately assume he's some random troll.