He has an outstanding reputation all around the world and is trusted by left leaning allies all over the world doing interviews with countless heads of states or opposition leaders.
He also was a reputable journalist even before the Snowden stuff do to work that investigated many of the evils of the Bush administration.
https://www.politico.com/story/2013/06/edward-snowden-nsa-le...
Whether you've misremembered it or you are accurately reporting Barton Gellman's claim it appears to be totally and utterly false. That's not super-surprising, it would be everywhere and in every story about Snowden's leak and exile if it were true.
"The Post just barely beat The Guardian in publishing the PRISM story on Thursday by about 20 minutes — "
"Gellman told The Huffington Post last week that he “started to hear some footsteps, so I had to move” on the PRISM story. There’s no question it was a race to publish, and although Gellman said he “would have been happier to have had a day or two” longer on the story, the Post had to move to get that scoop online before The Guardian."
https://www.rollingstone.com/culture/culture-news/snowden-an...
Snowden, who was one of Greenwald’s longtime readers, tells me in an e-mail. “Glenn tells the truth no matter the cost, and that matters.”
Then Greenwald parlayed having Snowden approach him into becoming a celebrity journalist. So Greenwald is a guy who takes a lot of credit for being in the right place at the right time and someone else handing him a scoop. Exactly the kind of person I wouldn't trust.