It's not just printing, it's tracking orders, packaging, shipping, or contracting for same and all the back and forth to sort that out, and it doesn't sound like Stephen has finished revising/writing the 2nd ed. It's a lot of work and presumably he has a full-time business to attend to. Sure you can slap a PDF up on a print on demand site and call it good but would that produce a quality product he would be happy with? Just speculating here of course.