I would need to be clear on the following before positing an answer:

1st - definitions (feel free to correct as necessary):

appropriate - (verb) to take (something) for one's own use, typically without the owner's permission.

exploit - (verb) to make full use of and derive benefit from (a resource)

2nd - questions
a. in order to NOT appropriate Black culture, whose permission should one obtain?
b. how exactly are we defining "Black culture"? (seriously)

my answers:
appropriate - no (again, whose permission does He need to get? if the Black folks in his band say cool, is that enough?)
exploit - no (mainly because I would have a hard time identify what specifically of his whole deal is purely ours)

off topic questions i would have related to the subject:
1. can a Black person appropriate/exploit Black culture?
2. is exploitation or appropriation inherently a bad thing? if not - where exactly is the line before it BECOMES bad?
3. do some folks get passes (e.g. Teena Marie), and if so why?