Is the classism in question really about being poor?

From my perspective, it is about perpetuating the stereotype that rural people are 'slack jawed yokels'. If this guy was from a vertical trailer park (i.e. a high rise condo unit), we wouldn't think twice about it because, despite being potentially just as poor, he is an 'enlightened city dweller'.

There's a rural vs urban component, but yes, it's about being poor. If he were poor and urban, a similar article would have talked about him growing up in the "mean streets" of some poor neighborhood. It's the same reaction.

Perhaps it's a regional thing then, because where I come from, trailer parks are essentially cottages for the middle class. The poor connotation isn't there, but the lack of population density certainly is.

I disagree. It was classism and credentialism that almost kept him out of science. What's amazing is that through perseverance and luck he overcame that exclusion. The story contradicts the just-world implications of classism, and so I believe this article doesn't perpetuate it; it cuts against it.