What kind of damage could this do? Islamists who watch American media will note the exceptions McCain listed and tell their operatives that they will not need to prepare for waterboarding and can prepare for less rigorous techniques. While it isn't quite the same thing as telling them all of the approved techniques, it gives another edge to the Islamists -- an edge we didn't need to give them.
Serious and responsible people would understand this. Apparently, John McCain doesn't qualify as either.
Please, can we have a modicum of seriousness?