Everyone knows it's illegal to text while driving stopped or not. The asshat is not the cop but the person getting the ticket. So it's easier to catch people while stopped, big deal. He's not getting out of doing work, he's more efficient at it.
Wish there was more like him, the speeders doing a few over the limit pose less of a threat than all these kids out there swerving between lanes and holding up the road at every red light that turns green. Even if the light is long enough for it to not bother you, it bothered that last car that got stopped at a red because they were the one who's chance was wasted.
The real issue here is why are people so addicted to their phones that things can't wait until they get where they're going or pull over to a parking lot. It wasn't that long ago you didn't get calls or texts while in your car. You're in your car to get somewhere, focus on that 'till you're done. Most people in the world today are barely intelligent enough to remember to think and drive at the same time, without bringing more tasks into the equation.
“Think of how stupid the average person is, and realize half of them are stupider than that.” George Carlin