Legal guarding position

[Adam]

MTD,
Your two plays have nothing to do with verticality. It has everything to do with the players jumping and being allowed to land at their destination without a new impediment.
Change your plays to have the players jumping slightly horizontally. Many officials will call a foul on B1 in the first play because he wasn't vertical. None I know of would call it on A1 in the 2nd for not being vertical.
We all agree that if A1 has verticality in the original play, he's clear. However, you seem to be the only one saying that his vertical space includes the area above his extended leg.