There are several likely explanations:
1. He is a counter-example to the claim that intelligent design advocates are being persecuted by academia. He is an intelligent design advocate who is also a professor at Lehigh University. (Point due to Tegamai Bopsulai.)
2. He has become something of a heretic in intelligent design circles as a result of his latest book, The Edge of Evolution, in which he affirms common ancestry, he calls using the Bible as a science textbook "silly," he doesn't think intelligent design is necessary to explain lower taxonomic levels of life such as species, genera, families, and orders, and he doesn't see the need for continued miraculous interventions into the process of evolution by God. (Points due to Larry Arnhart.)
3. His latest book conflicts with the idea of The Fall when he argues that malaria was intentionally designed to kill people. (Where's Ben Stein on this one? Point due to RBH.)
It appears that ID's big tent has become too small to allow Michael Behe to remain inside.
Larry Arnhart at Darwinian Conservatism
Brian Switek at Laelaps
John Lynch at Stranger Fruit