Keeping the elephants away
Except at Columbine. And yesterday in the high school in California. And Virginia Tech. The latter, ironically, being cited by the guy on the radio as a reason his Texas public school board authorized teachers to carry concealed weapons. Except, as in Utah, this is another example of keeping the elephants away. Texas hasn't had a mass shooting at a school in 30 years. Longer than that, actually: the last mass shooting at a Texas school was the infamous assault by Charles Whitman on the UT campus in 1966. The last mass shooting in Texas was more recent (2009), but it was at a place with a lot of armed people around: Fort Hood, Texas.
Still, you can't argue with success. I'm sure he hasn't seen any elephants near his school, either.
So it's a double benefit!