I absolutely do defend the right to yell "fire!" in a movie theater. I also absolutely think you are subject to the consequences thereof.
If there IS a fire, then by all means yell "fire!" accordingly.
I've twice seen Penn Jillette stand on stage before thousands, juggling flaming torches, pontificating loudly about and proceeding to yell "fire!"
I've seen the movie _Backdraft_ in a movie theater; there was much yelling of "fire!" therein.
And, of course, if you scare a crowd into a life-threatening stampede by yelling "fire!" when there isn't one, then you're culpable for any harm that follows.
All of this is different from what you portrayed, which was incarcerating someone for yelling "fire!" in a theater purely on grounds of doing so, regardless of whether there was/wasn't a fire and whether (in case there was) it posed a threat.