And if they wanted to make an example of Snowden, the last place they want him is in an American court of law, with cameras and stuff. Gitmo or some other extra-legal incarceration isn't much better, if it's public.

The best example would be for him to be disappeared. Let his encrypted secrets come to light, so it's obvious that he's either dead or getting tortured somewhere, and that the American government simply doesn't care about diplomatic niceties when it comes to silencing whistleblowers. That would be a lesson to the wary.