That is to say, without the screw, there is no motorcycle; without the motorcycle, there is no screw. In this concept, things cannot exist without being connected, dependent, and intertwined with one another. There is nothing that exists independently.
I won't defend the book vigorously, but your reading of this part seems both superficial and easily dismissed with a moments thought. Pirsig is obviously driving at something deeper, even if you don't think he completely gets there.
It's a book about thinking and changing how you do it, after all. You can't expect to get much out of something like that if you can't or won't examine your own cognitive bias as you do.