As I drove down the street, he was behind me in his vehicle and followed me for 2 kilometres until he drew beside me at a set of lights. I never looked at him but had a fair idea what he was doing until the lights changed

At a couple of points during the chase, he turned off to the left, but soon caught up which suggests that holding the phone whilst behind the wheel was not the only traffic offence he committed.
I found an interesting article covering how ambiguous the rules on photography in public can be.
http://www.capturemag.com.au/advice/kno ... -in-public