To the best of my knowledge, the US has never executed anyone for treason under Federal law other than the Lincoln assassins. John Brown was convicted of breaking a state-level treason law. The Rosenbergs were done for violations of the 1917 Espionage Acts, and not for treason.

How does a halfway respected newspaper like the Philly Inquirer publish such pap?

Treason charges for Snowden would be rare, challenging