The problem is there's no threat against anyone, and K-State is a public university receiving Federal funding.
You can't just kick the guy out for a tweet. I know that's going to enrage most of you, but the school is going to have to dig deep to find a legally defensible reason for kicking the kid out. Don't say who cares. Part of the job of an administrator is minimizing risk, and you don't expose yourself to litigation that you could easily lose just because some kid posts a bullshit tweet.