He's a lawyer and an amateur historian, after all; both those career fields are conducive to wordiness.
It's true. The assertion, anyway, I'd never heard of the actual guy.
Regarding the OP, one thing I don't think you'd see is sapient life developing on both planets, unless sapience is 1)broadly defined, in which case we've got fellow sapients running around on Earth or 2)is extremely more common than we ever thought, which runs sharply afoul of our own paleontological experience.
The window, as we know it, is too small.
Also, it's an open question how much you can economically exploit a gravity well, especially from inside another gravity well. Even if you got colonization efforts going, you'd have two global economies that, short of intangible culture, could almost not interact.
It would be nice to have a back-up planet, however.