New York Times V. United States
Publishing confidential information is not illegal. Getting it is, but publishing it's a protected practice of journalism.
also depends on how you got it. if it was just given to him without him seeking out someone to go get it, then no, it isnt technically illegal, but, if he told someone to go get it and give to him, yes, it would be illegal.
as for treason, it isnt treason to print something like that, especially as a non citizen.