Imagine you were trying to measure whether or not increasing X proportionally increases Y. Now imagine you first sort your data points, Xi and Yi, independently -- it will now misleadingly appear like Y increases when X increases since the variables are both sorted. You've scrambled your data (Xi, Yi) to be (Xk, Yj). So you're essentially working with a totally different dataset now.
It's actually quite a simple question, just asked using a lot of overly complex language which probably confused the questioner and his boss.
It's no different to having a list of key/value pairs and sorting the keys and the values independently, and hoping to get a meaningful result which is absurd.
