Purim is not one story of Jewish memory; it is the story of Jewish memory as a perpetually evolving, perpetually animating impulse. How brilliant is our tradition for giving us this Memory Week, with its multiple narrations of the same Amalek!
What causes otherwise decent and loving people like this to defend genocide in God's name? I think the problem lies in the basic approach they take to reading the Bible.
Remember that we Jews have learned the hard way that unthinkable evil can quickly become a reality; that those who call for Israel's destruction have to be taken seriously.