The story I'm hearing elsewhere is he pulled the alarm to delay the vote, as Republicans are violating their "72 hours to read the bill" rule they agreed to at the start of this Congressional term.

While I don't condone the actions, the result was a delay, long enough for representatives to read a bill they are voting on, which is something that should always be allowed.

If only people got this riled up whenever the other side broke the rules...

Reading a bill is part of a normal procedure and the outcome is more important. So, while I don't condone the action, at the end of the day, if the outcome benefits people other than himself, then I can understand his action. The thing is they weren't given enough time to read as Republicans violated their own 72 hours to read the bill rule.

Yelling fire in a crowded theater has been protected speech for decades now.

You would have to prove intent, which is almost impossible. I accidentally set off a fire alarm once. The relevant signage was totally ambiguous and not even remotely clear.

That actually is protected speech. Brandenburg v. Ohio