What I am hearing is that silk is not a necessary component of knotting the Paspaley way
You can't see the knots and they are put on a foundation of nonstetch thread.
They are invisible so why use silk at all? Paspaley pearls are heavy and ordinary knotting with silk would really stretch from the weight.
Maybe they use Spectra too
In fact the way I finish my strands is to double back through the pearls and knot around the foundation thread for one to three beads/pearls.
I also noticed that Kari of Kari pearls describes a similar method with a foundation thread and she knots all the down it, not just the first and last three like I do.