It's a good debate. And even better test. It's something marketers should test and run with what gets the best result - most likely measured by lead quality, volume, and sales.
His finidings through testing were that when he requested a zip code up front, his initial click-through rates were lower, but his response rates on the back end were much higher. It turned out that people who gave a little information up front were much more likely to give a lot more later on. It really boils down to trust.