Ok, package just arrived from Amazon. You get two protectors for the $10. Guess one is for cleaning.
The microfiber cloth is super slick feeling, almost like silk. It is also about a thick as maybe 2 pieces of notebook paper, way thinner than the foam pad that comes between the keyboard and screen from the factory. Folded where you have 4 thicknesses and compared to the foam, the foam is still thicker. No way it would transfer prints to the screen that I could see.
I will try using it, it can’t hurt! I agree with barkomatic and do not think this whole thing is anything to lose sleep over. My MBP 16 is carried in a sleeve with nothing ever sitting on top of it.