It was some technical detail about browser cookies. I don't remember what. But it was hardly the height of computer science.
Regardless of whether he considered what I said to be tactful or not - a 3 day silent treatment broken only by a contract representative is a ridiculous response.
My real point though is that he (and a lot of people) are more concerned with appearances than with actual good results. This relates to the term I used in another HN thread - the Kumbaya Approach to project management.