I don't think it was BS. He had a minor injury, and they did not want to risk aggravating the injury. The rest was to help him avoid worse injury. The international friendly period was a good time to give him some rest to recover. The guy plays 2-3 games a week. He needs a break. If Argentina had important games, they would have played him with that minor injury. It was just not worth to risk him for games that did not matter at all. Barca games are for competitive games and not friendly games, and they do matter.