6: Every project longer than a day must have an engineering plan, no exceptions. There is nothing more guaranteed to blow up a project than realizing weeks (or months in) that a requirement was missed.
Apart from that it is a good start for a manifesto - just needs a meme handle (≈agile).
Hi! Author here. The principles are roughly ordered from start -> end of a project, with the exception of the last. Principle 6 is specifically about how something is built, the preceding ones are about what to build. I can see how it could be a bit unclear.