The laws against carrying knives without good reason are not there because of idiots, but because of people with messed up moral compasses, rubbish impulse control, violent tendencies and a general willingness to maim or murder rather than take perceived slights or risk losing face with their equally messed up peers. They undoubtedly catch a lot of idiots.
I for one loath the present idea that because it is not possible to prevent our social dregs from committing crimes, society is happy to ban or criminalise whole swathes of objects so that merely carrying or possessing them becomes the crime, whether there was any intent to cause harm or not. I know it is law, and I follow the law to the best of my ability, but that doesn't mean I think it is right or that I am happy with it, or that I would want to help it be enforced at every opportunity.
This young chap sounds to us about how we all sound to the rest of the public. I agree that his taste sounds pretty dreadful, and that he is a bit of an idiot, but he has a job, likes knives and wants to be able to use the tools he likes. In my book that is no different from someone liking their Gransfors and carrying it on camping trips or carrying a locking folder on a building site. I have done plenty of camping in the UK and not needed an axe and I know that people manage on job sites with knives by Stanley.
Showing an interest, acting friendly so that someone is put at ease, then reporting them to the police is, I think, pretty scummy behaviour. Who here would want that to happen to themselves? Out for a walk somewhere that they think they can justify carrying a Mora and Wildlife hatchet, meet a someone walking a dog or hiking who expresses interest in bushcraft, have a nice chat, then later find this person reported them to the police as a possible danger to society!?!
I think the lad needs to be told that he is on thin ice, that he is not creating a good impression and that he is increasing the risks faced by everyone else with whom he shares his interest....and that even for big knives, his choices are rubbish. Maybe the message will go in, maybe it won't. It stands a better chance from making an impact from someone who knows what they are on about and has knowledge rather than someone who is merely nervous and fearful.