ah, sweet mystery of the magic eight ball. it is as if you have captured a dream, only to leave it just beyond our reach. I love the shapes that reach up to the top of the frame and then veer away, confused. many directions going on here, to symbolize the ficklenes of the magic 8 ball. There is only one score I can give such a picture: 8
I believe the intention of the challenge was to take a b&w photo in color mode. This is why desaturation was discouraged. I don't think the challenge was to shoot a color photo with b&W in it. It may be a suttle difference in interpretation.
Yes you have a black and white object and meet the minimum requirement for the challenge. The placement of the 8 ball doesn't really make sense and the clutter in the background won't help the score of this image.
What a bizarre place for an 8 ball to be! Of course, that's what makes this a very interesting photo. Outside of this challenge, this would look really good as a true B/W.