Very good question. I don't know why it is specified. There has been a long list of cleaning / lubricating substances suggested. It is on my list to find out. My suspicion is that it is meant to be pure, thopugh, considering we are talking about plastic coated cable, it isd most likely to avoid nylon's biggest enemy, acid. The answer to this question is on my list for the next PIA symposium in Reno late February. Maybe I'll see you there.
