It's not the fact that he did the right thing, it's the fact that he deliberately put himself in a position where he could do the wrong thing, and was proud enough of the fact that he didn't that he posted a thread about it. For the sake of illustrating the point, let's reverse the situation and all you guys out there imagine your g/f going out to the bar with a guy friend that she spent some months doing the nasty with before you guys got together. You know there's attraction and chemistry, and you know there's alcohol, and you know ethical judgement may well be impared in the spirit of the moment...
Now say she comes back to you and tells you that nothing happened. You may believe her, but you wonder if deep down she might have wanted something to happen. You sure as hell know that the other guy wanted it to happen.. And then you wonder just how strong your relationship really is.