his misunderstandings are understandable.

Many of them are shaped by his experience at Microsoft. Which mostly means that he misunderstands many things in a Microsoft-centric way. But it sometimes means other things. For example at Microsoft his job, back when he was technical, was to produce design specs for Microsoft Excel. Having had the job of producing a big design up front, he is going to have a certain emotional commitment to the idea that this is a worthwhile thing to do.

To be fair, big design up front clearly was the right thing to do for a company like Microsoft which was shipping shrinkwrap and had large costs for each new rev that they put out. The idea of a weekly rev with incremental feedback would have simply not worked.

However the barrier that you have is that people usually can't really tell how much they like something before they see it in action. Which is why fast prototypes and incremental development help design out.

Cheers,
Ben