>I also think it should have been fairly obvious to the casino employees that some kind of advantage play was happening.There's an interesting side story to this. While Ivey was conducting this scheme at the Borgata, a famous advantage gambler named Don Johnson happened to be there at the same time. Johnson is mostly famous for beating Atlantic City casinos out of $15M playing blackjack using their overly generous rebate policies for the highest of rollers, though he has also made hundreds of millions of dollars beating horse racing using algorithms that he paid to have created. Bloomberg did a 45 minute video on him [1] and here's a writeup if you prefer [2]. Johnson and Ivey are friends.
When Johnson walked by the high limit room and happened to see Phil playing baccarat with piles of $100,000 plaques in front of him, accompanied by a woman that he normally wouldn't be with, he immediately knew that something wasn't right. He walked up and tried to talk to Phil, who told him "it's not a good time right now". Don said "au contraire my friend, I don't know what's going on but it looks like a great time" lol. Johnson actually sat down and, figuring that Ivey knew what he was doing, copied Ivey's bets until Ivey made it known that he was serious about being alone with his companion at the table. Johnson won but was not sued or asked to return the money. Johnson told this story on an advantage gambling podcast [3].
So yes, anyone that knew anything about Phil should have instantly known that he would not be playing a negative expectation game for such high stakes without an advantage. Having heard several gaming attorneys weigh in on this issue, I do believe that the current decision in the US will be overturned, although it is unlikely that the case in London will be.
[1] https://www.youtube.com/watch?v=hJpnnaksXNM
[2] http://www.theatlantic.com/magazine/archive/2012/04/the-man-...
[3] https://youtu.be/tpJ7djdrm_c?t=27m52s