It's certainly possible that this research shows correlation between less emotional thinking and language use, but it seems to me like Mandela's quote in the article is really a reframing of Goethe's observation that "The border of our world is the border of our language." It's no different really than the Romans and various "barbarian" tribes exchanging youth to grow up in each other's culture - know your "enemy," speak his language, etc. That explains more about Mandela's cognizant motivations in this case, though the vignette makes for a nice article.
