That guy just keeps repeating "it's hard" then 'explaining' why in obtuse terms and in ways that don't stand up (I don't think he understands database behaviour

That guy just keeps repeating "it's hard" then 'explaining' why in obtuse terms and in ways that don't stand up (I don't think he understands database behaviour). Frankly I don't think he has much experience in this area. I'm going to give up now, he's spent a fair bit of your and my time and still can't accept he's not right.