The Trump campaign literally has no argument to make in front of SCOTUS. Bush vs Gore was decided on the basis that different recount processes within the state violated due process; whether the ruling was right or wrong, it was procedural in nature and rooted in what would 'harm' the voters. There's no similar argument to make here...Once you mail your ballot, you have officially cast it - you cannot change your mind. A vote postmarked on November 3rd is the exact same as an in person vote on November 3rd, and voters are not harmed by how long it takes to count the vote they cast (it's not like every in person vote is counted on Election Day, either). Bush vs Gore was a matter of exploiting judicial philosophy, this would be a matter of creating something out of absolutely nothing.