I don’t think you understand the point of hypotheticals. They’re not meant to be taken literal. It’s more of a wisdom check as opposed to an intelligence check, honestly.

It wouldn’t save time to just say the sound can’t make it, either. Even if we were doing things your way… that proceeds to leave the original premise of the hypothetical unsolved, meaning we would need to make an entirely new hypothetical to demonstrate the sound/light speed difference. If we take everything literally, it takes us more time.

Additionally, just in case you think hypotheticals are useless entirely and we should just say the facts, helping people “visualize” things is a part of the point. Examples, demonstrations, and so on are ways of teaching things, which is similar to what this hypothetical was attempting to achieve.