I'm told that game theorists often have arguments over a similar sort of situation:

In a competitive game with another person, it's often necessary to assume that they'll behave rationally in order to determine what your best strategy is. (If they'll choose randomly and erratically, the nature of the rules might make it impossible to determine which of the options is better.)

But what about the cases where there are, say, two strategies which are equally good if the opponent is rational but only one of which is better if they act irrationally? Is it consistent, some argue, to both assume that the opponent will be rational and to say that the one strategy is better?

I say that human beings can screw up, and the second option lets you hedge your bets without risking or losing anything. So there's potential benefit but no potential cost, so you should not view the two as equally good.