"No we can't - folk isn't a "style" it's a process identified with a social group
Your list is how one of the most prolific composer on it describes himself - "a contemporary song-maker who makes songs using folk styles"
If he rejected the description "folk song writer" who the hell is anybody here to contradict him!

How do you know whoever he "rejected the description ~ folk song writer" if he is using folk styles he is doing what contemporary folk song writer do! He may well not be writing in the genre of course and therefore not be a folk song writer and of course be a popular song writer! Yes not all contemporary songs are folk songs!

It is the style, the content of the subject matter and intention of the writer and of course of the intended audience that defines whether it is a folk song or not

No no traditional and folk song are not the same thing no matter how much you would like it be

Ray