I see no evidence that merely being convicted of treason is enough to get you thrown in a solitary cell forever. There's a long list of plain old convicted spies[1], and they just went to regular, run of the mill prison. I would like to see the evidence that Snowden would be treated any differently.

And again, I'm not saying he would've been protected as a whistleblower, just that he had to choose one or the other: take his chances as a martyr for freedom, or escape all consequences and with them, his legacy as a respectable historical figure. He chose the latter.

[1] https://en.wikipedia.org/wiki/List_of_imprisoned_spies