Did this last week without enough "drying time" and had to walk some stretches, but the more that I think about it, so what?
The premise of the question was mistaken. One can get through - even on a bad day half of it is rideable and the whole thing its only about a twenty minute *walk* so that is not a reason to avoid the Westchester trails if the day itself is nice.
That said, muddy on the way up is a nice incentive to push on to Brewster, or consider a different return such as past Tarrytown Lakes and down the hill to the train there.