Art.
While, IMO most of the Graffiti called ‘art’, is an attempt to legitimize a subculture, from what I’ve seen I would slide him into the Art category.
Funny story.
Last year we went to the Whitney Museum.
My youngest, after about 3 floors, pulls my wife down close and says...
“Mommy, there are a lot of scribbles in here”.
Art Linkletter would have been proud.