I would say there are probably many other parents who had exactly the same situation and had to cope, possibly they could have travelled to other parts of the country just in case, but they followed the rules. In any case, the rules concerning people with autism didn’t change until 9th April so they aren’t relevant to the first journey.
The second journey to Barnard Castle was after the rules changed, so there might be something there but I’m not sure that’s what the change in rules were meant for - why travel 30 miles, there’s plenty of closer places with peace and quiet.
Has it actually been confirmed about the autism? If it has, it makes the scrum outside his house with child in arms more distasteful.