Whatever happened or happens to Nusrat Fateh Ali Khan makes no difference to the ruling in the Islamic Shariah that Music is Haram. But I respectfully suggest to ask your own teacher about the Authenticity of the story, If he has that he had verified it then there is no further need to check for Authenticity. If he says that he has heard it then ask, "Should you be relating stories about someone who has died without confirming it, first"?