 Bendor and Swistak's results must be interpreted with some care. First, one should keep in mind that no probabilistic or noise-sensitive strategies can fit the definitions of either “nice” or “retaliatory” strategies. Furthermore, imperfect versions of TFT do not satisfy rwb-stability. They can be overthrown by arbitrarily small invasions of deterministic TFT or, indeed, by arbitrary small invasions of any less imperfect TFT. Second, one must remember that the results about minimal stabilizing frequencies only concern weak stability. If the number of generations is large compared with the original population (as it often is in biological applications), a population that is initially composed entirely of players employing the same maximally robust strategy, could well admit a sequence of small invading groups that eventually reduces the original strategy to less than half of the population. At that point the original strategy could be overthrown.