This could be a new entry in the Annals Of Audiophile Foolishness.
While I personally prefer natural fibers in my listening environment, I would not suggest that synthetics can't also do a good job, because they can.
We use the blow-through test on fabrics sometimes as a shortcut to tell whether sound will get through a fabric--in the case that we want the sound to get through the fabric. Under what circumstances would you want your carpet to pass sound? I can only imagine using a carpet to damp the sound, so in that case you are looking for absorption, not transmission.