I worked with a lot of engineers in my 40+ year engineering career. One thing that most engineers don't like is ambiguity. I didn't like it either, until mid career when I was thrown into an environment where the customers didn't really know what they wanted, and it was impossible to explore all of the solution space within time and budget constraints. I ended up thriving in this environment, but I watched as many qualified and experienced engineers floundered and over-stressed themselves. The attrition rate in this environment was about 80%. To survive, I had to use intuition, speculation, and innovation -- things I had not used much in my previous engineering roles. I sadly watched while a lot of really good engineers chose to move on, or were assigned to less relevant roles.

In this case, I perceive that the author (Jose) was looking for firm requirements, and did what he could to elicit them, but the Kagi folks were just looking for innovation and a demonstration of competency. They didn't care as much about the details of the submittal as they did about seeing what the candidate would do without specific requirements.