> Makes the conspiracy theories regarding journalist Michael Hastings' death in 2013 seem more plausible.
Not really. The possibility of taking over unmodified cars remotely was not very widely known at the time. An organization that knew about that and had the technology to actually do so would not want to use it except on high value targets that they could not reach by more conventional means, because they would want to keep this capability under the radar of potential targets for as long as possible.
Due to the nature of his work Hastings would have been easy to take out by conventional means. He was an investigative reporter. It would be easy to feed him a lead on some story, like some important political person having a connection to a drug gang, and set up a meeting in a sketchy part of town with someone who says they want to give him confidential information about that. There would be nothing suspicious about that, and it would be easy to arrange for this fake meeting to go bad and end up with Hastings dead.
This would look like a sad but not totally unexpected way for a bold, risk taking, investigative reporter to die, and there would be not even a hint of a connection to any government agency.
If his car did not have remote vulnerabilities, and so any takeover involved modifying the car, then killing him by car takeover is even more absurd. It runs the risk of the modifications being discovered between the time they are installed and the time they are used (what if he takes his car in for service and the mechanic finds them?), and if used in a place where the agency doing the assassination does not have control of the scene afterwards risks the mods being discovered in the wreckage.