Snowden could of done all of this anonymously ala “Deep Throat”. He outed himself for the 15 minutes of fame.
The WaPo was in contact with the Feds. He wouldn’t have been anonymous long in this environment.
Coming forward might actually improve his safety. Snowden implied the federal government makes people—I presume terrorists—disappear. Snowden could have very well died from an unexpected heart attack or something if he hadn’t come forward. By making himself a public figure, he might be improving his odds...sorry to say.