I believe that anything that helps students 'relate to' science/math (or any other needed subject) should be encouraged.
The essential question to ask is: "Would this (in this case, rap) help students to overcome the 'fear and loathing' with which most students view math? Would it help them learn science more effectively"
Without having constructed any models on the issue to help guide me, I understand the following: What rap seems to have done for those students featured in the article is to help provide an essential link between something they already know (rap) and science (about which they are required to learn something). I quote:
?For many students who are not successful, this is just something that they know how to do.?
If I were a teacher, I personally would not know how to use rap to help students relate to science or math. But more power to anything that helps students overcome their 'fear and loathing' of math or science - which I believe is a real problem that needs resolving if it exists. I do not understand at all the objections raised.