Actually, it’s about a drug experience, not a dealer. The Tambourine Man is not a dealer - it’s the experience. That’s my interpretation. I’m not a poet - that’s the best I describe it.
But this is a discussion on music and poetry, not values.
It could be either. But does it really matter? Dylan left it up to the listener to unravel the mystery, and that's just fine with me. A lot of his best songs were that way.
I love the Byrds' version of the song, but it's a shame they never (to the best of my knowledge) recorded the complete version as Dylan wrote it.