Yelling fire(falsely) in a theater wasn't an example of breach of contract that is prohibited by a private agreement, but an understanding that the government has the right to prohibit speech made with the specific intent to create criminal harm. It's also not, as far as I understand, not the current legal standard, as of 2010's Holder vs. Humanitarian Law Project.

>Speech can never be a crime

Speech can be a crime. Google limitations on free speech. The specific example you gave is in fact a crime.

But in this case the intent is to cause harm which is a crime, not merely saying the words. Thats why the crime is "yelling fire in a crowded theater" not just "yelling fire". Notice the difference and how it becomes a completely different action altogether despite saying the same thing.

I don't think it's fair to say speech can be a crime on its own.

>But in this case the intent is to cause harm which is a crime

This is a fundamental misunderstanding. Intent is a necessary component of the crime, just like intent is necessary component of most crimes. The intent to cause harm is not the crime.

>Thats why the crime is "yelling fire in a crowded theater" not just "yelling fire". Notice the difference and how it becomes a completely different action altogether despite saying the same thing.

Actions in themselves aren't universally crimes in all contexts, that doesn't mean they aren't crimes in specific contexts.

If what you are trying to argue is that no string of words can be a crime to utter in any context, then yes you are correct, but by that standard no individual action can be labeled criminal.

>I don't think it's fair to say speech can be a crime on its own.

SCOTUS has ruled many times that all speech isn't protected by the first amendment. Some speech can be made, and has been made criminal.