This is such a good story. I remember reading it when my son was a toddler. It was one of the first times I started to internalize one of the most important parenting lessons I've learned being a Dad:

Never say 'no' to something unless there's an obvious safety issue.

Especially don't say 'no' just because you don't understand the request: that's the time to show them that you're curious about what they're thinking and give them practice explaining their reasoning in a safe and comfortable situation. Kids need freedom to explore their world.