To answer your question:
Protecting a whistleblower's identity is in the interest of US society as a whole. It protects the individual somewhat from persecution which in turn encourages people to blow the whistle on illegal activities, thus benefiting society.
I can't claim to know anything about ciarmella's background, save what hyper-partisan, conservative outlets have spewed. But absent more even-handed coverage, or rebuttals from liberal and left-leaning outlets, the details of his personal history, and affiliations do seem to merit some level of public scrutiny. Anyone interested can look him up on Breitbart, conservapedia /wikispooks, or through any other connservativr outlet (oddly enough, not fox last time I checked). But I'd rather not link to those rags if I'm not confident of the veracity of the information within.