Don't know how highwayman stands legally (I doubt if even JD knows a case on that one!) but I don't think it's unreasonable to refuse such fares, and morally I think the other driver was in the wrong - it's people like him that make it more difficult to refuse the 'chimpanzees' tea party' brigade.
We may let people eat occassionaly for whatever reason (to keep the peace, for example), but who willingly lets people eat takeaways in their motor.
I love (hate actually) the ones who say don't worry, the won't spill a drop - well it's rare that they don't leave at least a crumb or two, but with someone pi$$ed, in a moving car, in the dark then it's hardly surprising.
I remember a few years ago picking up some plonkers who just had to go to the kebab shop on the way home - since it was a good fare my wallet got the better of me and I said nothing.
It was an out-of-towner and thus in the dark, and one of them in the back had on a pair of cream-coloured chinos, and was clearly eating his kebab.
When we got to the other end his chinos were covered with red chilli sauce, but miraculously the seats were unmarked
If I was highwayman I would just tell it like it is, and he should be OK.