Bit idea

It is a time of miracles! In the first miracle - the dems take the house, get more seats in the senate, and Biden wins. In the second miracle - Biden says "We will pack the court." Note that he goes whole hog and doesn't even say "expand". The third miracle is he actually he says they have the votes and they will pass the law in Biden's first 100 days even though Fetterman is suddenly squishy and hints he might "jump ship" but he doesn't elaborate.

In the meantime all six GOP justices do something extremely unusual. They give interviews to very friendly right-wing media outlets. They say they have discovered a legal concept which means they can find court expansion unconstitutional. In the fourth miracle - the dems create a filibuster carveout and pass their court expansion law and threaten to "do something drastic" if the GOP justices find it unconstitutional. Lib experts all say "The conservative justices are bluffing. They cannot do this!"

The court rules 9-0 that it's unconstitutional. The 3 lib justices again issue a sharp concurrence. A few days later Justice Kagan is caught on a hot mic saying "I would have voted with the conservative judges anyway. A 6-3 ruling would cause the public to lose faith in the court as an institution. Even worse it would damage the all-important comity that exists between the justices."