Some of you are having a comprehension problem. The OP's phone wasn't confiscated. At the beginning of the movie, everyone was asked to please turn their cell phones off. OP (and probably a couple others in the theater) thought that they were unique! Their cell phones have a vibrate mode. They can use text messaging without talking! Therefore, they're above the rule and can do what they want.
The theater deals with these people the fairest way possible - they give them a CHOICE.
The cell phone stays at the front of the theater, safely locked up, since the user has proven that they can't follow the rules. OR, the person can leave the theater. Actually, there was one other choice: turn it off at the beginning of the movie.
As far as "emergencies", bullshit. 99.999% of what happens to the majority of individuals is NOT an emergency. Your best friend's girlfriend just broke up with him, and he needs someone to comfort him? NOT an emergency. If you can solve an emergency by sending a text message back, it wasn't an emergency.
That's not to say that there aren't individuals who genuinely have emergencies on a regular basis. Heart transplant surgeons, volunteer firemen and EMT's, and a few others regularly have emergencies. It's sort of an unwritten understanding that those few individuals have a valid reason for leaving their phones on vibrate. Is it reasonable to tell other individuals to put their lives on hold because there is a reasonable chance of an emergency? i.e. wife is 8 1/2 months pregnant, Gramma's been in the hospital for a month with a terminal condition, etc. So what if these people bend the rules slightly and leave their phones on vibrate so they can quickly check a message. If there's an emergency, they *leave*. They don't sit there texting.
The vast majority of the rest of us: there is NOT going to be an emergency during the 1 1/2 hours of a movie that can't wait for us to be in the theater lobby to answer. Your life isn't that dramatic, get over yourself.
As far as how distracting one cell phone is,
A. (as pointed out) Just how, then, did theater security pick the OP out from the crowd?
B. If everyone in the theater thought the same way, there'd be a heck of a lot more than just one.
Kudos to the theater management.