A Brief Objection to the Conjunction of Schaffer's Contrastivisms

To begin, I want to consider a sentence that I think I understand.

S. Jones knows that Suzy’s throwing the rock caused the window to break.

By claiming to understand this sentence, I do not mean to suggest I have complete and fully worked out views providing informative analyses of knowledge or causation. I simply claim that the sentence makes sense to me. A helpful comparison is to a sentence like this:

S’. Jones knows that Suzy’s throwing rather than tossing the rock caused the window to break rather than shatter, rather than that Billy’s throwing rather than tossing the rock caused the window to break rather than shatter.

While I don't claim that I am outright unable to parse such a sentence, S seems comprehensible to me in a way that S' does not. And this is the basis of one concern I have surrounding the conjunction of Jonathan Schaffer's contrastivisms.