He pointed something out which I thought was a great business lesson: if you can't explain yourself in 5 minutes or less, you are going to be in trouble.
Relating this to pg's story, it means: you have to be able to express your ideas cleanly, succintly, and then forget all about them so you can take feedback. You have to drop the fact that it's "your idea" and just listen to what is being said.
I've worked with a number of people who were really, really, really excellent technically, but you could literally see the cogs churning in their head as you were speaking to them. And it was very much like what Paul describes, a sort of glazed over look. Afterwards, you'd have to rev the same idea with the a few times until they got it, or until you had to give up and make a decision by yourself.
I think it's a hard habit for some people to break, but it can be done.