Gorsuch pondered, too, whether voters would be able to recall their mail-in ballots if a scandal involving their candidate (like a “sexual escapade or colluding with a foreign power,” he said) broke out after Election Day.
It's so weird and fucked up that he's making this an argument against allowing postmarked ballots, which allow someone to wait until election day in case there are surprise scandals. He seems to think someone being able to recall a vote for someone who's revealed to be unfit would be bad.
But instead of this hypothetical where a scandal comes out after polls close and some small number of people are able cancel votes sent from far away, he wants people to lock in their vote well before election day so that they can't vote with the information available right up to the end like in person voters. And I wouldn't be at all surprised if the next case he'll be decrying early voting for doing just that.