The reason you can't yell "FIRE" in a crowded theater

I am a little tired of hearing that "you can't yell 'FIRE' in a crowded theater" as an example of where the First Amendment does not apply.  A theater is privately owned and the owner CAN limit speech if he so chooses . . . and probably would. Congress, on the other hand, cannot limit speech.  Period. But what if it is a government-owned theater?  Government-owned theaters are not authorized by the Constitution and, therefore, are unconstitutional.  See how easy that is.  Who needs a law degree?  But I am not a Supreme Court Justice, apparently this is how a Supreme Court Justice thinks: