Earlier quoted context omitted.
http://en.wikipedia.org/wiki/Upper_middle_class#Income 10 Million households have $1 million+. There are an estimated 111,162,259 households in the US... This is upper class wealth...just not completely elite levels of wealth. I think the point of the article is that people with upper class levels of wealth tend to have upper-middle class lifestyles.
This is really an argument of semantics of "upper-middle-class" vs. "upper-class." Maybe there's standard definition I don't know about. My personal definition is that upper class is "don't need to work ever again." You're right that upper middle class people have the same lifestyles as upper class. The difference isn't in material goods, it's in freedom.
The interesting component of the article was that the average income of somebody with $1 million of net worth was approaching $400,000. This implies a poor savings rate and not very much savings at all.
If freedom is the goal, it seems the key component is a modest lifestyle.