I tend to agree, but then again it isn't really about mercy, is it? It's about conquest--in this case conquest of the spirit.
There are other weapons in our arsenal besides Western materialism. Sufism, for one. It's the antinomian mode in Islamic society, and it exists (however tenuously) outside of Sharia.
Then there is the greatest weapon of all: the Gospel of Jesus Christ. Evangelical Christianity is the fastest growing religion in the world today, and it is taking the majority of its growth in Africa and in the Catholic heartland of Latin America. Perhaps they can turn their attentions to the more fertile and less damaging (to the West) ground of the Islamic Middle East.