As you know, that's May in Wisconsin. The weather changes rapidly and, for the marathoner, usually not in a positive direction. Madison could jump up to the weekend before Green Bay and be no bigger of a conflict with Green Bay than it is now while, on average, getting more reasonable weather.
At the very least, if they are going to cancel the thing mid-race again, they should have a good plan in place. From what I have been hearing, apparently they didn't use 2006 as a learning experience and the cancellation was not well organized.