Is anyone going to bring up the fact that Michael Jackson, (in 1984, pic related) didn't look "black" very much anyway. If I'd just arrived on earth back then from a spaceship, I'd have assumed he was Hispanic, but not black.
Conclusion: Any white guy in 1984 wouldn't have worn "black shoe polish" in "blackface costume" to mimic Michael Jackson anyway. The costume would been an epic fail, and this is the most asinine 'cover story' for blackening one's face in 1984 I've ever heard of!