The difference between game theory and decision theory is that in game theory you need to worry about not just what is rational for you to do, you also have to consider what is rational for the other players to do.

That seems to be necessary somewhere along the line when implementing decision theory too. If you don't model the other agents in the system you will (obviously) end up making worse decisions.

So, what is your analysis of what they would do to a small number of their customers who violate their rules by using real-time machine assistance? They can't take those people to court. People who, if they were allowed to get away with it, would destroy the online poker business. Would it be rational for the Poker houses to try to cheat the rule-breakers?

I don't make such analysis. I assume the worst case with respect to them choosing among plausible methods of reciprocation and instead focus on the logistics of whether calculator use can be detected.

The house cheating seems to be a rather benign situation. The probability that the cards being dealt this bad or worse over multiple hands given fair deals can be calculated. If there is a high probability that the house is cheating you stop.