I certainly agree with your point. Managers who insist on making technical decisions better left to developers are a real problem and even more so in larger organizations.
As a consultant to large government and financial organizations, I run across this very often. I usually respond with a detailed and written technical explanation of what the industry standard best practices are and why they are applicable to the client's specific circumstances. With a smaller client, that is often enough to change their minds. With a large organization, sometimes you just have to do it their way and wait for it to fail. When that happens, you have already documented that you know what the problem is and how to fix it. And if it doesn't fail, then at the very least you have strengthened your image as a "team player". And on rare occasions, you will find that the client was actually correct for their particular situation.