Ironically, if he hasn't done any such testing, the answers would be much easier to generate. "We haven't done any." Not that the NHTSA would take it well....
I've been involved in writing similar descriptions to provide to NASA, and when you get down to exactly how each module works and need to enumerate every branch, it ends up being a lot of work.
It would appear that he didn't have any interest in cooperating at all, though. Which inevitably leads me to wonder if it's not more of a face-saving maneuver; better to blame failure on the pesky regulators than admit your technology isn't up to the investor pitches you might have made.
Also, the documentation being asked for is something the company should be able to put together fairly easily because they ought to have asked and answered these questions along the way to building the product.
Have you ever considered establishing product direction through use cases branded as "stories" and pulling them out of your ass every two weeks?
/s
"Describe in detail the features of the comma one"
and
"Provide a detailed description of the conditions under which you believe a vehicle equipped with comma one may operate safely ... [and] a detailed description of the basis for your response to [the previous question] including a description of any testing or analysis..."
and
"Describe in detail any steps you have taken to ensure that the installation of the comma one ... does not have unintended consequences..."
I'm not saying the request is unreasonable, but to say that "the information requested is not that great" isn't really true. To completely answer those questions would take a lot of effort. (Assuming of course that he's done such testing. His canceling the product rather than respond makes you think he realized his answers would not be credible...)