Those parts of the emails are valid to report on. Stuff like a staffer thinking Lessig is smug is not valid to report on.
Who determines what is "valid" to report on?
Good reporters report on the part that matters, bad reporters just try to find something salacious to poke a bee hive.
Yeah, except "the part that matters" is never some objective category valid for all places, times, and people. This site used to have a tagline about "stuff that matters," but the reality is that a lot of the stuff posted here didn't "matter" to the vast majority of people in the world. Meanwhile, a lot of stuff that "matters" to the vast majority of the world wouldn't be of interest to a significant portion of the audience here (e.g., sports, celebrity gossip).
Here's the reality of journalism -- the "news" is mostly about selling stuff, NOT informing people. Yes, "good journalists" who want to be respected generally tend to focus on certain topics and ignore others, but they are conscious of the "bottom line" like everyone else. And if some reporter claims to be completely oblivious to stuff like that, you can darn well bet their editor isn't.
So, the question is rarely "Is this too salacious to be 'legitimate' news, or does it 'matter'?" The question is usually, "We know that this will get a lot of clicks/sell a lot of ads/papers/whatever. But will it piss off our readership or advertisers if we do so?" Somewhere down the list, far below that set of concerns about revenue, maintaining readers and advertisers, etc., are things like, "Is this 'respectable journalism'?" Or, "Does this matter?"
Because, let's be honest here -- even if something appears to be "too salacious" to be a story, if it gets caught up by SOME major media source, eventually most of the other major media will start reporting on it. You don't want to be the newspaper or whatever who steps "out of line" and starts looking like a cheap tabloid, but as long as everybody else is writing about it, it's gonna be fair game.
What really "matters"? Human life? Well, most Americans (even educated liberal well-meaning and loving ones) don't really have much interest in African news. I mean, some say they do -- but they really don't care about reading about that stuff every day, even if every day is pretty much a bad day for millions of people in Africa.
Meanwhile, is the Queen of England having another great-grandchild?!? Let's devote weeks of news for that. Does that "matter"? I don't mean to pick on the royals -- any celebrity gossip will do. Or what about sports? Does that really "matter"? It's certainly not going to have as much of an impact as that genocidal African dictator, but editors know that there are loads of people who basically pull the "sports section" out a newspaper (or do the equivalent online) and ignore most of the rest.
But to bring this back to the current political stuff and scandals, we basically end up in a situation where fans of politician A think stuff "doesn't matter" and publishing it is "salacious" but people who don't like politician A definitely think it matters. To many fans of Bill Clinton, the various scandals about possible affairs and interns "didn't matter" compared to his leadership capabilities as President. To some Trump fans, clearly his views on women also "don't matter" to the evaluation of his leadership abilities. (I'm not equating these two people or their actions by any means, just noting similar reactions I've noted among fans.)
To those fans, publishing a bunch of stories about such stuff is just "salacious" and yellow journalism, which is targeting stuff that should be irrelevant to their political life. To others, this "matters" deeply and it's irresponsible NOT to publish something that tells you something about their "character."
Anyhow, getting to TFA, the question of where information came from is WAY down the list, far below other ethical concerns about journalistic "integrity" and reputations of the media source and individual reporter. (Note that I'm assuming the information is verifiable, as much of it seems to be in the present case. Obviously if there was a question of whether the information was even true, that's a separate issue. But assuming it is believed to be true, it's really unfathomable to me that most modern journalists would ignore a story simply on the basis of where the information came from... legal or not. Even if they tried not to report, other media sources would, and then they'd be duty bound to do so as well to avoid being left behind in coverage.)