Personally I wear light clothing/clothing with reflective clothing, and always have lights on if its gloomy enough that they make a difference. I believe that even if I have the right to wear dark clothing or not have my lights on, ultimately it's me that will pay if a driver doesn't see me and hits me. I'm aware that the precautions I take don't guarantee my safety but I can make it easier for drivers to see me and thus make myself (at least feel) safer. I don't need to do this, and drivers should be paying enough attention to see me regardless, but they are human and therefore not perfect, and if I can reduce the chances of me being hit why wouldn't I?
On one commute once unknown to me my back light failed, a driver overtook me, stopped and told me my light wasn't working. He then offered to drive behind my until we got into the better lit local town so that no one else would come up behind me and hit me because they didn't see me.I had a spare light with me so just swapped the light but I really appreciated the offer. I think its a shame we now seem live in a world where we fear to express our concern for others safety. Who knows what would have happened to me if that driver hadn't stopped. I hope that if you approach the subject from a place of concern and friendliness that most people will take your 'interference' at face value and even if they then ignore your concerns, will appreciate your concern. The driver who stopped for me could have sworn out the window at me for not being 'properly' lit up, and I'd probably have just given him the finger and ignored what he said, but because he was decent, I responded in kind.
I think how we say what we have to say matters far more than what we have to say. Perhaps if you see him again and its safe to do so, stop and explain why you're concerned about him.