Code for he doesn't fit the lone white guy ...gun nut theory....
Or, more simply, that they don't want to tip anyone off that they're a suspect so's maybe they can catch the sumbitch. From what we've seen thus far, it appears that the shooter is paying attention to the media coverage. No point in making it harder to find the bastard.
Of course, you'll see what you want to see and hear what you want to hear. I'm betting on this being a lone whack-job who finally snapped a while back. I'm sure, though, that if it turns out to be a single shooter, you'll be on FR howling that the suspect is a patsy.
Snidely