You do lose the line of clouds, but that is why this challenge was about going out and taking a photo with consideration to the Rule of Thirds, rather than cropping an existing photo to achieve the result. If you had taken the Rule of Thirds into account when at the location, you could have achieved a result that included both the cloud and the foreground, by recomposing etc.
Nice colours in your photo and the relection of sky in the wet sand is great.