I'd agree with the other dude that Joe's new answer sounds way more palatable, it's clearly designed to be, real or not. They probably had a think tank work on this during the time Biden was stalling and dodging.
Specifically it's designed to play to the left and the right, to depress Trump's turnout, and improve Biden's by not scaring the more reasonable lefties or abandoning the pro-packing ones. If the SCOTUS was magically non-partisan, lefties consider it a win by not getting handmaiden'd, righties who believe Biden will stop worrying about a battalion of new blue SCOTUS judges declaring the 1'st and 2'nd amendments fake and gay.
With lefties energized and more gullible righties placated, assuming Biden wins, he can assemble a scholar team of Antifa professors and RINO's to just regurgitate whatever plan the Dems already have written somewhere.