Carrier sensing MAC protocols have limited utility in underwater acoustic networks because the propagation delay is not small relative to the packet duration. A recent publication shows simulated results that would appear superior to those predicted by accepted theoretical analysis. We compare the simulated performance against theoretical predictions, then provide an independent simulation of the same scenario and conclude that the CSMA results originally published are equivalent to the CSMA results that would be observed with no propagation delay. This is a reminder of the importance of independently verified results, even for simulations. We then provide what we consider to be corrected results and outline an effort to further validate underwater acoustic MAC protocols with both simulation and in-water tests.