Bit cheeky, what does one have to do to be considered a "cyclist"?
Not ride on the pavement, and get some lights, I'd say....
Like others have said, tell him once to get it off your conscience. If you feel generous, the poundland lights gift is a good idea. Sounds like he's not too bothered about his safety (I'm not referring to the helmet, I don't wear one myself), but if you know him well enough, something along the lines of "Hey, mate, you know you're being a tit riding like that and with no lights, don't you? And breaking the law. Grow up and get sorted out." might work. If he takes offence, he's not worth having as a mate.
A lot of people seem very ignorant of the law, but then a lot of people seem to be generally ignorant of a lot of things.
On the 'proper' cyclist front, I'm quite willing to be a snob about it. Ride a bike legally, safely, and with lights, like I do, and you're a cyclist, like me. Doesn't matter what your bike is, or what you wear, whether you're a lycra clad roadie or an old lady on a shopper, or a student on a Tesco Special BSO.
Ride on the pavement (when it's not shared use), jump red lights, don't have lights on in the dark, weave in and out of pedestrians or cars dangerously, and you're just a pillock who happens to be on a bike.
So my snobbery, I like to think, is based on high moral principles, and not class, or economic grounds. I realise it's still snobbery, but hey, that's just me.