The argument (which I don't agree with, but which has some merit) is that he and his accomplice used knowledge available only to them which constituted a fraud against the casino.
The reason I don't agree with it is that the fact that the cards were printed in a manner which made it possible to do this does not mean they defrauded the casino, it means the casino shouldn't have agreed to use those cards because their security folks should have known about this issue.
No, the arguments is not that is it fraud, that's addressed in the article, "Ivey did not commit fraud, Judge Noel Hillman for the U.S. District of New Jersey wrote in an opinion on Monday." The argument is it the game wasn't legal under New Jersey law as one party knowingly used marked cards. The judge believes that the fact that they didn't mark the cards themselves isn't important.
The reason I don't agree with it is that the fact that the cards were printed in a manner which made it possible to do this does not mean they defrauded the casino, it means the casino shouldn't have agreed to use those cards because their security folks should have known about this issue.