The first glyph of every line – a hint at a cipher?

[dashstofsk]

which makes the hoax hypothesis a bit less plausible

You will need to explain how you have come to that conclusion. The p-effect seems just to show that pages that have a raised frequency of lines starting p have a raised frequency of gallow words. I cannot see how this supports any of the meaningful text hypotheses, continuous narrative, natural language, shorthand or cypher.