What you don't like is the law... Fine, just don't keep saying he won't get a fair trial because according to the LAW he will. Saying he won't get a fair trial is wrong. The courts are there to fairly apply the law and for the most part, that's what they do.
You cannot have a fair trial governed by unfair laws. Jim Crow laws were brutally unjust. Are you seriously going to claim that the rulings under Jim Crow laws were in any way fair or just? Just because something is the law does not mean trials will be fair. It is a trivial exercise to write laws that clearly prevent a fair trial under any reasonable definition of the term "fair". You seem to have a fairly mechanical definition of the word fair. Just because something follows the law does not mean it is fair. Under your logic anything a dictator does is fair because he is applying the law interpreted correctly. That's a ridiculous argument.
Although it seems obvious to me that the laws on treason are fairly clear and even handed
I guess it's fortunate you aren't a lawyer then because it's not at all clear that the actions of Mr. Snowden constitute treason. In fact it's rather easy to argue that they do not under the US Constitution which puts some rather strict limits on the definition of treason. He did not levy war against the US and it's debatable whether he gave aid and comfort to the enemies of the US. Convictions or even indictments for treason in the US are quite rare. The most recent was in 2006 and the last before that was in 1952. Mr. Snowden's actions would likely be considered a felony rather than treason. Daniel Ellsberg who released the Pentagon Papers wasn't charged with treason nor were numerous captured spys and others who released confidential documents.
I'm not sure how you think the law can be changed so Snowden get's what you think is a fair result, without letting other folks off who really *should* be convicted.
The law doesn't have to be changed at all. The justice department merely has to decline to prosecute or the President can grant a pardon. Happens all the time. The next guy can be prosecuted or not under the same set of rules without changing anything or causing any serious problems.