Here's the president of the censorious Sinclair Community College in Dayton defending his school's restrictions on protest signs:

Colleges have an obligation to protect students, employees and visitors in an era when acts of domestic terrorism have captured headlines, said [Steve] Johnson. Concerns about campus violence have spiked, he said, since the 1999 massacre at Columbine High School in Colorado and the 2007 Virginia Tech shootings in which 33 people died.

Columbine caught the attention of educational institutions nationwide, Johnson said, serving as a 9/11 to campuses everywhere. "And Virginia Tech was the second 9/11."

Although Johnson said he can't imagine how "words on (a) sign would make a person unsafe," he did say protest signs could be used as weapons.

"It has nothing to do with what was printed on those objects," he said, "but what those objects could be used for."