Think Progress says this morning's little show was about fear mongering. That could be it, but I think that narrative has sort of passed us by for the moment. Not that people aren't genuinely concerned about this stuff, but we've finally passed the stage when jumping up and shouting "evil doers!" will get the desired response.
I think it's more about letting Bush do something he enjoys for a change. And what he seems to enjoy doing most of all is giving speeches about evil doers.