You're right they probably wouldn't be able to to it, but that child isn't being marketed as an invaluable business tool to assist doctors in diagnosing cancer, or whatever.
A non-English speaking adult wouldn't be able to answer the question either, after the question was translated to their language. Maybe you wouldn't want a non-English speaker helping you to write an acrostic in English. Luckily nobody is marketing LLMs as "great for designing word puzzles" though.
