The bot does bluff, and in fact it learns from self-play that bluffing is (sometimes) the optimal thing to do. At the end of the day, bluffing is simply betting when you have a weak hand. The bot learns from experience that when it bets with a weak hand, the opponent (another copy of itself) sometimes folds and it makes more money than if it hadn't bet. The bot doesn't view it as deceptive or dishonest. It just views it as the action that makes it the most money.

Of course, a key part of bluffing is getting the probabilities right. You can't always bluff and you can't never bluff, because that would make you too predictable. But our self-play and search algorithms are designed to get those probabilities right.