I actually have a theory on why Nate Silver is dragging his feet-
I'm sure his forecast has Biden somewhere around 90%- he doesn't want to release it now, and risk Trump making a comeback and winning, and then he'd have to deal with all these idiots who will hammer him about being wrong because they don't understand how stuff like that works- thus he'll wait until either Trump narrows the gap or we get to the point where he has zero chance of winning
If Silver is really doing that then he should be ashamed of himself. Taking criticism is part of his field of work.