Koberna also faces possible suspension or expulsion from Kent.
"Any threat to our campus community is taken seriously and immediately investigated," said university president Lester Lefton. "Our students, employees, and all those who come to campus should know that their safety is our top priority."
On Twitter, friends of Koberna expressed shock at his arrest.
"Holy sh*t I can't believe bill got arrested for a tweet," said Ashley Mikulec. "If they saw half of his tweets and took them seriously he'd be in a mental asylum."