re: Is the Kuiper Belt Slowing the author's neurons?
I hope the rest of the article's reliability is better, but the two Pioneer probes were launched thirteen months apart, not 'within a month of each other', and from Cape Canaveral, which had been officially renamed in 1971.
Teasing aside -- an intriguing theory. How does it relate to Voyager probe deceleration, as observed or not observed?