Just because the evidence is not going to be remotely in your favor doesn't mean you won't get a fair trial. That, and given what he has done, solitary confinement for ~30 years is relatively light compared to execution. That, and if they finally decide to prosecute people that have helped him, without regard to profession, they might not get too bad of a deal.
On the other hand, what Snowden and his friends are asking to not have a fair trial, since they want exceptions here and there. In addition, there were people unfortunate enough to lose clearances to his actions yet they will not get the same ability to call that privilege.