An American Letter Bomb Can't Be Terrorism

I got an email from S.R. pointing me to a lengthy post by David Niewert of Orcinus, who noted that the mail bomb received by Don Logan, the director of the City of Scottsdale's Office of Diversity and Dialogue, on Feb. 27 is being called by law enforcement an "isolated incident" or an "ordinary crime" that obviously has nothing, nothing! to do with domestic terrorism. If the mail bomb targeted at Don Logan isn't terrorism, what is? Does it qualify as terrorism only if the return address is in Arabic?