The First Amendment contains no such requirement to run leaked documents past the government first. This can be an ethical decision on the part of the publisher, but the notion that the First Amendment only covers publishing after government input has been sought is a dangerous one. This assertion by Comey also just isn’t true. As Trevor Timm pointed out on Twitter, Wikileaks has attempted to contact the US government in the past before publication, but has been ignored.
Furthermore, Comey and Sasse both claim Wikileaks’ publications have caused some sort of damage to government employees. They offered unproven assertions it has endangered lives, even though the evidence shows the worst the US government (and its employees) suffered is some embarrassment.
The only mitigating factor was Comey’s assertion that the DOJ isn’t interested in using espionage laws to prosecute journalists for publishing leaked documents. As he correctly points out, the culpability lies with the person leaking the documents, not the journalists publishing them. Of course, this statement isn’t being made in a vacuum. It’s being made in the current political climate where the president has expressed an interest in reducing free speech protections. The DOJ itself appears to be working towards prosecuting Julian Assange for publishing leaked documents. All that can really be gathered from Comey’s assertions is that the DOJ may not prosecute journalists who run everything past the government before publication.