I also think we're OK reproducing the above verbatim, as the document's licensing page states: "No part of this publication may be reproduced or transmitted for commercial purposes, such as selling copies of this publication or for providing paid-for support services." Since we're not selling it, nor providing paid-for support services, I think we're OK to use it.

Yeah, that's exactly what I was going to say.

Apple can't copyright the "recipe" (the commands needed to remove Classic) but they can copyright their embodiment of the recipe (the supporting text and the text as a whole, the commands wrapped in the support text). To avoid infringing copyright the text would need to be rewritten.