Speech codes restricting?

Doing my hw for Issues on speech codes, I found that most speech codes are necessary. FIRE makes it seem like a simple rule "directly restricts the first amendment," however I believe most of the codes are not restrictions, but guidelines to ensure a safe and peaceful environment that a school should have. For example, I looked at NIU and FIRE rated them a "red light" school. Looking over the speech codes described as a "red light," I found they are there for the purpose of protecting the students and their right to learn in peace. The only thing the speech code "restricts" is the behaviors and speeches of people that will directly disturb, harass, or threaten another student.