[Jurassic Referee]

Originally Posted by Camron Rust

The airborne player was only going to be able to reach that spot by going through the defender. The defender already earned the right to block that particular direction of movement.
But, 4-23-3c allows them to move laterally or obliquely to maintain position. And, as long as they're in the path of the opponent, they're maintaining it. The right to maintain position doesn't disappear just because the opponent is airborne....only the right to obtain a new LGP. If, however, the opponent has jumped in a path to the defender's side (is airborne), they've lost LGP and it is too late to gain a new position with A1 being airborne.

1) And fwiw, that's basically what I've been trying to say also. The defender didn't commit an illegal act under any rule that I'm aware of.