I don't think that anyone is advocating lowering the price in response to requirements changes, etc. I think the idea is that the initial price might be lower.
Well, he literally says longer turnaround for a lower price. I don't see why you would lower the price for a longer turnaround? I know people do do it, but, because it makes no sense usually (there are ofcourse exceptions here and there), it often ends negatively for 'the provider'.
I did not mean changing the price in the middle of a project. I meant finding clients with needs and expectations that fit well with yours. For example, one of my long-time clients has very flexible production schedules and I am willing to give him a reduced rate for that because I can fill his project in when I have time.