I've seen lots of responses like this one and this one (from our old friend Ben Stein!). From the first link:

By the cop's own admission, he (the cop) "pumped his foot slowly up and down in response." In other words, Craig asked for sex using an arcane code extremely unlikely to "alarm, anger, or disturb" -- according to the the equally arcane code defining disorderly conduct in Minnesota -- an uninitiated fellow-lavator, and the cop knew what it meant and said yes.
Where's the victim?

I'm somewhat sympathetic to this view, and I'm toward the end of the spectrum allowing people to have sex with whoever they want and not get hassled about it. And yet, apparently this sting was initiated because the police had received complaints about this particular bathroom in this particular airport.

So I answer a question with a question: If you're the Minnesota police, and you're receiving complaints about public sex in an area open to citizens of all ages, including kids, just exactly what the hell do you do about it?

If you install a video camera in a bathroom, how does that not horribly infringe on people's rights? And how do you unobtrusively stake out a bathroom? No, I think you go about it pretty much the way they did. You send in an undercover officer. And to what extent does the officer go to make an arrest? I think it's reasonable to stop short of any actual lewd act, which the officer did.

Here's the actual police report, if you're interested. Craig didn't just "tap his foot". He stood outside the stalls for a while, acting nervous. Then he moved into the stall next to the officer, and blocked the door with his suitcase. Then there were a series of exchanges with the feet, and finally Craig reached under the stall. Taken individually, none of his acts seems all that suspicious, but in total you have to admit he was soliciting for something. And by his own admission he was. He pleaded guilty. Seems like a pretty clear cut case, so I'm not sure why so many people are defending him.

That said, I think these people that get caught from stings should be punished nowhere nearly as severely as people caught in the actual act. I don't think asking or planning to have sex with someone illegally (e.g. with a minor or in a public place) should be a crime of the same degree as actually committing the act.

So I'm all down with Craig getting a slap on the wrist. Should he have resigned? I don't know. There was probably immense pressure for him to resign from the Republican Party to "put it all behind them" in the ongoing perpetual election cycle.

But to those who are trying to say he was "just tapping his foot", I say, come on. He was guilty, and he was caught, and the police went about it just right. But was what he did all that bad? Not really.