That is a very serious accusation against a very esteemed group of American heros.
Just because you served doesn't give you immunity from criticism later. Murtha served, and I think he should be stood up before a squad of Marines and shot for treason.
You're right: McCain was REALLY tortured. As such, he should damned well know that we haven't even come close to torturing anyone. I also find it the hight of disgusting that this bunch of "heros" somehow seem to be able to draw a moral equivalency between our enemies and us. We don't behead our enemies. We don't hijack planes full of civilians and fly them into buildings full of civilians. We don't shoot kneeling women in the back of the head because they were out of the house alone. We don't declare holy war against the Pope because he quoted someone. We don't riot over a cartoon. We don't drag the bodies of our enemies through the streets and spit on their corpses while our women scream "LULULULULULULULULU!".
We are NOTHING like our enemy, and would STILL be nothing like our enemy even if we WERE torturing prisoners for legitimate intel. The question, "Well, how can we expect our enemies to treat us well if we don't treat them well?" Excuse me? We feed them, house them, give them Korans, don't disturb them during prayers, and point them toward Mecca. What do we get for our troubles? Our troops are mutilated and hung from bridges. Yeah, being nice sure won us a lot.
They are playing politics, pure and simple, and their past military record, no matter how worthy of praise, doesn't change that. I fail to see how having "the interests of the American fighting man at heart" means that we grant Geneva Convention rights to terrorists who don't deserve them. How does that help our troops, other than making them a laughingstock to our enemies?
There is one and only one way to win a war, and that is to destroy the enemy and shatter his will to resist. You don't do it by codling him or treating him by rules he will use against you. You do it by beating him so soundly that he looks upon you in sheer terror and realizes that he never should have fought you in the first place. Once you reach that point, THEN you can build him back up at your leisure. You would think that a bunch of guys with that much military experience would be able to grasp such a basic concept. I'm glad we didn't fight WWII this way. We'd all be speaking German or Japanese.
ETA: I seem to recall the esteemed Senator McCain saying to Al Qaeda after 9/11, "May God have mercy on you, because we sure won't." One of those bastions of nobility in the death camp known as Guantanamo just happens to be the guy who MASTERMINDED 9/11. It would seem that the esteemed senator's memory is pretty short.