He wasn't booked cowardly though. That's why they held camera shots onto his face longer, to make sure to capture the conflict in his expressions. That's why he sat and contemplated before trying to revive the referee and go for the pin. A cowardly heel would have been smirking in the corner and ready to pounce once the Big Show laid out John Cena. But Punk -- at least not yet -- isn't that type of heel. He still wants to win matches the right way because when he says he's the best in the world, it's because he believes it, and he knows that the only way for everyone else to buy into it is to beat guys fairly.
Punk didn't do anything underhanded to John Cena between the bells. In fact, Punk was obviously reluctant to pin him and put him away. He eventually did it because, well, what else was he going to do? The championship was on the line and if you snooze, you lose. It was after the match, where he didn't help fight Big Show off of Cena, that he behaved "underhandedly" -- and even then, he wasn't. What good reason does Punk have to stop Cena from getting beat down post-match? He's not Cena's buddy. He has no dog in that fight and, as such, has no reason to get involved. Again, his facial expressions and mannerisms conveyed as much. He considered it, but there just wasn't any point, so he didn't.
The place you could argue that Punk was truly cowardly is in taking out The Rock, who he more or less ambushed. But I would argue that even there, nothing about his behavior was cowardly. He came at The Rock when he wasn't expecting it, but he didn't come at him with his back turned. That's a subtle, but key difference. He also hit the GTS very methodically. If he was truly a coward, he would have hit The Rock, snatched up the belt, and high tailed it. He also would have looked over his shoulder after he left the ring. Instead, he paced the ring slowly, hit his move, and walked out. He never looked back because he wasn't afraid of repercussions. Cowards, by nature (especially in wrestling), are squirmy. They get their licks and get the hell out of Dodge, watching out for their own ass along the way. But not Punk. Not last night.
Now, that said, he may go back to being the cowardly, conniving heel. He may lie, cheat, and steal. He may cower away from challenges rather than embrace them. But last night at least, that sure didn't seem like the case.
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