I believe the intention of the challenge was to take a b&w photo in color mode. This is why desaturation was discouraged. To make it more challenging. 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.
Hmmm, if the home in the reflection is the subject, then it's yellow and not B&W...that aspect, plus the color in the plant and red wall push it out of the challenge for me.