His workplace is a public governmental building, so that seems like standard journalistic practice. It is also normal and appropriate to visit his house to seek a comment when he didn't respond through other channels. It would have been irresponsible and unethical to not put in an effort to speak with him before publishing this article. And taking a photo of a government official in public is again very normal, and it's good that they confirmed the vehicle is actually used by the guy they're naming.

For investigative journalism, if it even qualifies as that, this is pretty shallow. It's good work but it's just some public data and a couple hours of work, not a deep invasive investigation. It also is not freelance, this is a staff reporter for a decades-old publication.