Refused the box for Wall Balls

I did my second Hyrox 2 weeks ago in Berlin and, not having a nearby Hyrox gym or training partner, I was conscious of not squatting low enough so (after hearing him call out my squat depth repeatedly) I asked for the box to minimise no-reps
The judge refused. With all the noise I didn't catch the reason. What could the reason have been?

The only thing I can think of is that he could see that my overall technique was ok-ish and that using the box makes it too easy? I'm 5,10 so perhaps my height has something to do with it? Any ideas?