Why is Eustace the last American Man?

I think that Gilbert considers Eustace the last American man because he represents classical American values that have changed or simply been forgotten as we have entered the modern era.
Eustace lives in a much simpler world that most of us live in. His biggest challenger in the world isn’t a person vying for the same job or anything like that. It’s putting his skills as a human against those of Mother Nature. There is a mystique around the stereotypical cowboy. On the range with just a horse and a six-shooter as company, there are very few images that produce that “Badass” male idea. Everyone Eustace meets gets swept up in this idea and Gilbert is no different.
At times she almost seems obsessed with Eustace to a point of glossing over his faults. While she does mention how he has become like his father, she moves on rather quickly to further highlight another of Eustace’s accomplishments. This image of the frontiersman is almost addictive to some people, and once you’re under Eustace’s spell, as it appears Gilbert is, he can do no wrong. And when you only see one person like Eustace, it’s no surprise that it’s easy to label him the last American man.