Ha ha ha. That's the state of the Internet. Assert something stupid "texting at a light is not dangerous" And don't back it up with explanation or cite. Then when someone disagrees, with a logical argument (a non moving car at a green light is more likely to be rear ended), demand cites to oppose your uncited opinion.
What's the rule, he who demands cites first, wins?
Umm... no, it's called 'logic'. To put a more-formal title to it, it's called 'the null hypothesis' -- in this instance, texting at a stoplight is no more or less dangerous than merely sitting at the light and waiting for it to turn green. You came along and said that texting at stoplights was far more dangerous than sitting there; that's a positive assertion which retains the burden of proof (i.e., show evidence which supports your conclusion and which disproves the null hypothesis).
Also, stating that "a non-moving car at a green light is more likely to be rear-ended" is trivially true; your unstated presumption is that texting while waiting for the light to change is the cause for a sharp increase in these kinds of rear-end collisions (which you'd also need to show).