The law has, in essence, always implied that if you use any hand for anything other than driving, then an offence of "careless driving" is being committed. However (us) smokers tend to get away with it, unless you are caught in the act of lighting up as you are driving. Where they can obviously prove that your eyes are off the road to focus on the act of lighting... if you're moving....
Same as focussing on the ice cream heading for your mouth!!
However the incident you report is a "Jobsworth" incident. And should be argued. Regardless of the reason why he was on the phone - if he was parked sensibly and anchors engaged, then in my mind he should
not have been fined.!
In fact he did the sensible thing......