Yep, the SC can read the tea leaves like anyone else. If Biden wins, the conservative's on the court opinions become worthless if Dems increase the size of the court to 13. Kavanaugh, Gorsuch, and now Barrett all understand this. So electing Trump is the preservation of their own relevance.
Now this I disagree with also. The Democrats will not pack the court. Remove the filibuster in the Senate so that they can actually pass legislation over top of the Republican universal-obstruction efforts, sure. Admit DC and Puerto Rico as states, maybe. Pack the court no. Even if they should, they will not do it unless the SC forces their hand. The threat exists to try to prevent the SC from doing something so outrageously partisan that they're forced to.
Another attempt to pack the Supreme Court would be exceedingly controversial. Much worse, if successful it would vitiate the principle of
stare decisis that provides stability, predictability, and reliance on the great body of fundamental law that constitutes America's jurisprudential foundation.
"An interpretation [of the fundamental law] to be changed with each change of administration" would eliminate the rule of law.
In 1937 the Senate Judiciary Committee issued its Adverse Report that resoundingly rejected FDR's Judicial Reorganization Plan also known as his "Court-packing scheme."
Judicial Reorganization Plan
Senate Judiciary Committee Adverse Report June 7, 1937
[The Judicial Reorganization Plan] would subjugate the courts to the will of Congress and the President and thereby destroy the independence of the judiciary, the only certain shield of individual rights.
It contains the germ of a system of centralized administration of law that would enable an executive so minded to send his judges into every judicial district in the land to sit in judgment on controversies between the government and the citizen.
It points the way to the evasion of the Constitution and established the method whereby the people may be deprived of their right to pass upon all amendments of the fundamental law.
It stands now before the country, acknowledged by its proponents as a plan to force judicial interpretation of the Constitution, a proposal that violates every sacred tradition of American democracy.
Under the form of the Constitution it seeks to do that which is unconstitutional.
Its ultimate operation would be to make this government one of men rather than one of law, and its practical operation would be to make the Constitution what the executive or legislative branches of the government choose to say it is -- an interpretation to be changed with each change of administration.
It is a measure, which should be so emphatically rejected that its parallel will never again be presented to the free representatives of the free people of America.