Actually, that is not true at all.

http://www.nytimes.com/2015/06/25/us...or-threat.html

The "original" American terrorist was the white Oklahoma City bomber. The boy who shot up the people in the church recently was widely denounced as racist and the crime viewed as a hate crime.

In this case, this shooter's mental illness had been documented previously. They aren't making that up. You can be mentally ill AND a terrorist.