This was on HN earlier, the crucial detail was that the journalist was tweeting personal information for an NBC executive (his email address) which is a violation of Twitter's policies.
No it's not, because 1) it's a corporate email address, 2) it was posted online in other locations prior to the tweet being posted, and 3) Twitter states on their website: "If information was previously posted or displayed elsewhere on the Internet prior to being put on Twitter, it is not a violation of this policy."
It wasn't his personal address -- it was his easily google-able, systematically defined (firstname.lastname@nbcuni.com) corporate email address.