Its actions have shown in the last 10+ years that is not the case. It has detained, tortured and killed people extra-judicially. Even its own citizens. Making any appeals to the the quality of it judicial process is a bit silly at the moment.
So in other words it might not make sense to be afraid of that particular threat "charge of espionage" but it is not unreasonable for him to fear in general.
Remember the case how that Russian ex-KGB agent was poisoned with Polonium? There is little doubt it was the Russians doing it and they also wanted to make sure there would be little doubt (except hard evidence) that they did, so that everyone learns to fear opposing or criticizing them in the future.
It seems to me Assange and Manning are prime candidates for being turned into example for all to see.
There is little doubt it was the Russians
The most obvious suspect is oligarch Boris Berezovsky, a London refugee from Russia, accused of embezzlement at home, who is waging a fierce propaganda war with the current Russian government.
http://www.rt.com/news/berezovsky-litvinenko-murder-allegati...
The response of the grandparent was 'no' because US legal system can't technically touch him. My response to that was that I am not exactly sure if the world should trust US in light of its actions in the last 10 years.
You can't conduct an experiment to figure things out, if you can't then come back and conduct more experiment because the first one killed you.