I'm going to start with agreeing with
@Revoltingest and take it from there. Beyond how SCOTUS rules is the question of legitimacy. SCOTUS is seen as legitimate in big part by how the justices are chosen. Is the process seen as honorable or not?
The problem started with Merrick Garland. At least one Republican senator said that Garland was a good choice. If his nomination had proceeded in a normal way with hearings etc and 51 Senators voted against him, people would have of course grumbled but at a lower volume. Instead Mitch's attitude was "we have the power so **** you". And along the way there were specious justifications for not taking up his nomination.
Now we have another "we have the power so **** you" with totally obvious hypocrisy and lack of honor.
On the day when the Senate confirms whomever Donald nominates, qualified or not, I will no longer consider SCOTUS to be legitimate until a Democratic President and Senate redresses the power by putting two justices on the court as is perfectly legal and in accord with what Abraham Lincoln did. Full stop.