This was nothing more than a personal decision by Klinsman. If he wanted to go with a "youth movement" than he wouldn't have included Davis, Beckerman, Wondo or hell even Rimando, for their first world cups when they are all not going to be involved for 2018.
I will admit that I have a bias for Landon. He has been my favorite player since I started following soccer and I live in LA and go to 10+ Galaxy games a year. That said there is no way that he isn't in form and couldn't have helped this team. Two weeks ago against Portland he was the best player on the field by a mile.
This whole thing has really made me question Klinsman. Back when there were all those reports of tension in the locker room between the team, a big complaint from the native US players is that he didn't get how they operated. He was always harping on fitness and motivation and those players didn't like how it came across because he felt like they didn't understand them. This seems like confirmation that at some level he just doesn't get his team. I also question why would you do this and make a story and a big distraction. This is all anyone is talking about and will be until at least the start of the World Cup. He says that Landon was a little behind other players, which I don't buy, but lets say that is true. Is it worth making this the story of your World Cup team? I don't think so.