I don't think you thought this idea through, vi!
Most theaters are mulitplexes and simply don't have the personnel to actively patrol each theater. You'd have to have someone on the scene in each separate theater. Movie houses couldn't afford this.
Also, it would be more disruptive to try and eject a patron, even if they eventually cooperated, spoiling the movie experience while an usher got their attention and then made them get up and leave.
Moreover, there's a very good chance that a significant percentage of these transgressors would make a fuss or outright refuse to leave! The minimum wage teenager trying to get them to comply would be up against it.
Finally how would it be determined beyond any shadow of a doubt that the call being received wasn't an emergency, especially if the person disputed this? How, exactly, would this be resolved?
Instead of calling the high tech approach passive aggressive as you do, I call it
proactive and fool-proof and employee resource smart.