They probably inverted the neuroticism scale in order to make it consistent with the other four traits, most of which have positive connotations unlike neurotic

They probably inverted the neuroticism scale in order to make it consistent with the other four traits, most of which have positive connotations unlike neuroticism. One might argue about the labels, but there's nothing wrong with inverting a scale for convenience of presentation. The personality traits of famous historical people are well established and widely available online. I have no idea how accurate they are, but they do fulfill their role as easily recognizable stereotypes. In any case the author probably used a publicly available dataset and didn't just make it up.