This is, from my recollection, an incorrect assessment of Silver’s methodology.
He runs (continuous?) Monte Carlo simulations over his inputs, and when he says that there's an 80-20 chance in favour of candidate O, he's saying that 80% of the simulations resulted in a win for candidate O, not candidate R.
He runs (continuous?) Monte Carlo simulations over his inputs, and when he says that there's an 80-20 chance in favour of candidate O, he's saying that 80% of the simulations resulted in a win for candidate O, not candidate R.