“I’ll get hammered here, but I think it’s a hell of a lesson.
Do I like it ? No !”
How is it a hell of a lesson? Do you think we need to see a murder to understand its illegality?
What’s illegal about stomping on the flag or cutting it or putting it on fire ?
Are you equating stepping on the flag with murder? Stepping on the flag is not illegal (yes we have a flag code, no it's not enforceable, it's just a set of guidelines), unless it's not your property, then it's likely theft and destruction of property.
If it was his flag, the school is actually in the wrong, and could be liable under deprivation of rights under the color of authoriy. That's the beauty of free speech. If it's the school's flag, then he's in the wrong, and should be suspended.
I don't agree with what he said, but the school is a government entity, and they did, in fact, violate his freedom of speech IF, and only IF, the flag belonged to the teacher.