I don't really see the problem, beyond an interesting observation in languageing (marked ***) : someone saw a different part of the pie then you had intended to emphasize. If it's still the same pie - how are you to know what appeals to each person?

For all you know, what he meant by his descriptor and what you mean by it may be completely different...so is there any point in using the same words to mean different things, especially if Tom,Dick and Harry will have their 'own takes' too?

Had it been me, I would have shrugged and said "Of course" (if I didn't especially think the point was relevant to the exercise, without necessarily being wrong). Or, more realistically "good point. If that makes sense to you, do it like that".

***I think the best you can hope for is to constrain the scenario enough to produce the correct outcome and teach to the middle of the curve.

***Kicking your own butt because folks are doing something contra is non-productive - unless you can use it to better frame the directions.

Personally, I think telling them to 'use the whole body to make the cut' is about as equally open to confusion, and without specific setup, leads to even bigger problems. YMMV.