Caught between discourses of disease, health, and nation

In reading the chapter of caught between discourses of disease, health and nation on pg 47 second paragraph down I found my self very confused as to why they would appoint experts to study this problem. They were allowing immigrants to come in even though they knew it was going to be socially and economic draining. They knew their answer before it was going to happen but they still let it happen. I wonder why?