In reality, he didn't do it. Our Congress passed the Bipartisan Safer Communities Act last year after the Uvalde school massacre. One of the Texas U.S. senators, John Cornyn, voted for it; there were warnings from many that something like this would happen but few listened.
Some think online auctions will go under but as long as a seller goes through a dealer with an FFL, not much should change. Local gun shows where the majority of tables are private collections are toast. If an enterprising FFL holder wanted to make some easy cash, he would advertise his availability to be present at shows, initiate background checks and complete the 4473 forms. All without having to watch his table for thieves or negotiate sales of his own personal items.
I don't think that will happen very often, however.