EXACTLY. He was a JOURNALIST. The point is to kill someone who might be about to disclose something you don't want disclosed, and create a chilling effect preventing others who might consider disclosing, whistleblowing, leaking, or simply reporting such things from doing so for fear they too would be murdered. This WORKS. Killing someone in secret only performs the first function. This is the essence of the idiom "killing two birds with one stone." In this case, it's killing 1,000 (or more) journalists with one rigged car.
There is really no media shitstorm about Michael Hastings. It's practically over now. What stays long afterwards is the chilling effect sensed by journalists and would-be-whistleblowers - the fear that by disclosing or reporting on the wrong story, they too might find themselves up in smoke.