That's a load of bullshit.

I've tried telling a person (using a phone) to shut up once and quite frankly I'd never do it again. He caused a huge scene, shouted at me like crazy and even threatened to beat me up. He ended up being thrown out of the theater, but so what? My movie-going experience was already ruined. I missed 5-10 minutes of the most important part of the film and for the rest of the movie I was pissed off instead of enjoying the movie. People have enough stress in their lives as it is. When I go to the cinema after a long day of work, the last thing I look forward is arguing with a moron.

It's not about "growing a pair", it's about not wanting even more stress and confrontation in your already stressful life, especially when doing something that's supposed to help with that.

Instead of demanding movie-viewers to act like police officers, how about we demand the movie theater to do its job?