[mjn]

Unless Bloomberg is coercing internet providers into handing over his emails and getting secret court orders to record his web traffic, it doesn't seem like a very good comparison.

Investigating people, especially those with any kind of political, economic, cultural, academic, or other influence, based on publicly available information and whatever people are willing to tell you if you ask, is a pretty traditional part of American public life. There's no right to force people to be disinterested in what you do and refrain from writing articles about it, as long as they collect the information by legal means.