The Gemara relates how Rav Bibi emptied the entire content of the basket before them (causing everything to separate from each other,, Rashi) perhaps in order to avoid Borer Why is this in itself not an act of Borer?
Quick Search:
Quick Search Daf Insights:
The concept of Borer is to be Mesaken an item by selecting its bad parts (or good parts for the long term). Throwing it so that it will spread out is merely avoiding the necessity for fixing it.