Not really. The author is advocating to not be too attached from an ego perspective to an idea and trying different things to see what actually works. That's different from saying you can't do what you love and expect to make money.
Well this is a graduate level course so I wouldn't say it doesn't require any degree or work experience. In general the numbering scheme at CMU is xx-yyy where xx is the department code (15 for CS department) and yyy is the course number (where 500 and above is graduate level).
I quite liked the article but I agree with you that these are not really "first principles". Seem like the story was shoe-horned to fit the analogy. The author could have taken the same story and used it to illustrate the power of open questions such as "what do I know to be true" instead of first principles.