If they did a great job, and the price was right, I wouldn't let anything (including the porn) keep from going back. Like others posters, I don't expect to get chummy with my nail tech.
Who knows, maybe the guy accessed a porn sight by mistake? It happened to me at work (I clicked on what I thought was a legitimate link and wow, was I surprised!!). Unless you lingered and it was clear he was into it... If that happened to me, I would have said something to him at the time. Even if English was not his first language, he probably would have understood, "Shut that off. Right now!"
OTOH, nail salons are plentiful, so if this isn't to your liking, there's probably one down the street or around the corner.