I'm sure there's something in a director's briefing somewhere. But since it's print-on-demand, offering a hardcover is only a trivial amount of additional work as long as the page count is sufficient (which it is).
As is typical, the PDF will become available first, so we have a chance to fix any typos that people notice before anyone buys a print copy. You can always re-download a PDF that has been updated. Print copies a few weeks later.