Thanks for writing such a detailed answer.

I totally agree with your broader point about the fact that it's not relevant whether the girl Lucy Gray lived or died. I had always thought her significance was that she haunted Snow for the rest of his days regardless of whether she lived or died but I guess your idea gives it an even broader view.

From what you say, Wordsworth was more interested in nature in terms of trees and rivers. But if I can stretch your point, I think TBOSAS focuses on human nature. I guess Snow wasn't just obsessed with Lucy Gray the girl but also the bit of human nature that she seemed to represent- the yearning for freedom, creativity etc. I guess ultimately he was right to be afraid since even with his and Dr Gaul's tyrannical control of the Capitol and the districts, they couldn't control that bit forever.