It never even occurred to me to think about the "Vanderbilt dynasty" when writing about Thomas Vanderbilt. I wasn't even particularly aware that there was one. To me the name suggests Gloria Vanderbilt, who I think was a fashion designer or something, but beyond that I'm pretty clueless about what the name suggests. Sure, it does have kind of an upper-class sound, but to me it was pretty much just a name.
Anyway, I did try to describe Thomas Vanderbilt as having olive or medium-dark skin, suggesting that he wasn't as white as the name suggests but was of a mixed ethnic background. So he's certainly not meant to be a pureblooded descendant of some current "dynasty." And I didn't portray him as upper-class in any way.