Every FP says what the return window is. It's clearly stated. Your party ticket (I think -- they used to) says that the party starts at 7pm. I guess my point was that if someone were going to fault Disney for not enforcing a stated rule about flash photography, then they'd also have to disagree with them not enforcing things like FP times. You can't say, "Only enforce the rules I want".
My "enforcement" question was more for the "kick them out of the park" people. That seemed to be too much punishment for a fairly small offense. YMMV
Except, unfortunately, there's generally no way to tell the former from the latter when you're on the ride.
The "small offense" made me physically ill and ruined my day. Kick them out, confiscate their memory card, revoke their passes, put 'em on a plane...back where they came from...all are small punishments in my book. I just wish, I'd thrown up on them.
Is there a stated policy about throwing up on other guests?
. 
Of course your experiences are just as valid. But come on. Do folks here (maybe even you) use late FPs? Same thing. There's a "rule", that is currently unenforced, that says you're not supposed to. But people do and Disney allows it everyone is perfectly okay with it. To the point where people would really begin to protest if Disney started enforcing return times. There's a "rule" that says that people going to MNSSHP aren't supposed to enter until 7pm, but Disney allows party guests to enter at 4pm instead.
So the "rules" about FPs and party entrance are also really more of a suggestion. Same thing. Why should FP users and party goers be allowed to work the system but flash photo people be banned from the parks? Do you think the Guest base as a whole would be willing to give up early entry on party night and late FP use if it meant no more flash photos on rides? I wouldn't.
You've mentioned valid opinions ... I believe my enforcement questions are also valid. I'd be interested to know how you think a "no flash photography" rule could be fully and effectively enforced. Confiscate cameras on the way in? Stop the ride every time someone takes a flash and escort them off? Loudly announce over the music / dialogue of the ride "No Flahas Photography!" Seems to me that would be just as harmful to the experience. And are Disney's resources better spent monitoring flash photos on rides than say, keeping bathrooms clean or having a few more people up at GR? I'm only asking because you seem so sure it's possible and maybe I'm totally missing an obvious solution.
Of course, by that time, every single person screaming was probably egging the girls on. Nothing, short of stopping the ride and pulling the girls with the camera, would have solved it. My guess is that every time they heard someone yell "No Flash Photography!", they gleefully took another picture just to be snotty.
. It just isn't fair to those around you. It's not so nice to have a flash right in your eyes. Some guy did that to me on Peter Pan...our cars were just passing each other..and off went the flash. I was looking in the wrong direction at the wrong time...saw stars for about 30 seconds. 
Except the FP thing isn't a rule. Many people interpret it to be one, but the fact remains it is not one. It also benefits Disney more than it benefits us, as we'll likely spend more time in the shops and such and less time in line. That was the key design impetus behind the FP system.
However, with that said, I do agree with you to a point. Kicking them out of the park would be an overreaction, even if it did cause someone else issues.My "enforcement" question was more for the "kick them out of the park" people. That seemed to be too much punishment for a fairly small offense. YMMV
Except, unfortunately, there's generally no way to tell the former from the latter when you're on the ride.
Is there a stated policy about throwing up on other guests?
Please, tell me .... how can Disney stop behavior that they don't know is going to happen? It's not like annoying camera flashers announce as they get on the ride, "I'm going to take flash photos during this entire experience!" and Disney says, "Great! Have fun!" And if Disney DOES say "No flash photography" and someone keeps taking photos anyway (as someone upthread described), what exactly are they supposed to do to preserve the experience? Wouldn't stopping the ride, sending a security guard out to grab the offending photo-taker, including the inevitable confrontation that will take place, and then restarting the ride also kind of wreck the experience for everyone else?
