Really, it depends on your six-year-old. Like, are you asking if it's plausible that at least one six-year-old somewhere in the world would think that? Then yeah, sure. If you're asking whether an otherwise normal six-year-old would do that, it becomes less likely.

Human adults vary wildly in what they know and how they perceive the world to work. Children vary even more. I guarantee you there's a six-year-old somewhere who would make that leap. Even otherwise "smart" kids might think that way, just because of a gap in their knowledge. But I wouldn't say most of them would think that would work.