To me, this mostly tracks with what 538 has said on record about how their model works and the design philosophy behind parts of it. To me, what Nate means when he says "directionally the right approach in terms of our model's takeaways" is that these sorts of wild and unintuitive outcomes are part of the point of the way the model is constructed.

Specifically, that when you get off into the weird situations like Trump winning Washington state, it's likely something incredibly weird has happened - something that likely has no historical precedent, so it may actually be a more sane thing to do to assume that now almost everything is backwards and Biden would win a bunch of states he shouldn't either.

To me, this points to a general willingness in the 538 model to just go "who knows" and build in some room for insane things to happen on the fringes. The Friday podcast episode about the 538 model specifically mentions that they have large/fat tails on their distribution that make it nearly impossible for someone to get over 95% chances of winning on a national level, and these sorts of wild results seem like the outcome of that. If you bake in an assumption that there's always a 5% chance of something crazy happening, that chance has to come from something in the data somewhere that reflects the ability of that to happen numerically, and thus will have numerical outcomes that seem impossible.