Of course, it's just one guy. But he was a leader, and had a good video/audio presence, which counts for something. As many people have said, the terrorist effort is a combination of a killing program and a media program. If you can't cause deeply substantial damage, you can at least do showy damage that makes the evening news... and thereby scares more people.
If a suicide guy went kablam in the forest
With no one to hear him - no media chorus -
No victims but trees - would he still be a terrorist?
Or would it be better to call him an errorist?