One simple fight back, if you find yourself seated next to a pornography user, is to calmly pull out your Bible and start reading it. I travel with my Bible everywhere, and, while I’m not out to get a reaction from anyone nearby (I routinely read from Scripture everyday and I can cover a lot of ground on long haul flights), people notice. No one has ever said anything. Sometimes they smile, and sometimes they burrow a little more deeply into whatever they’re reading or watching, but they do notice.
But you are right. It would be nice if the Christian community would band together in a concerted response to these witless slobs.