The key difference between a Principal and Senior Developer is the pivot from what you know to who you know. Principal is meant to take initiatives and run with them. Senior Developers do the real work. Principals are called out by execs when they need to refer to ownership in a specific space. Senior Developer, not so much. I only glanced/searched at this individual's webpage briefly, but it seems like they weren't fully clicked for understanding organizational behavior. The difference between "what you know" and "who you know".