[Camron Rust]

If B1 is moving towards A1 at the time of contact (doesn't have LGP), it doesn't really matter what A1 did short of extending an arm to create contact or something intentional. I don't care if A1's shoulder is lowered or if A1 steps into B1. B1 already made the mistake by jumping towards A1. B1 only gets to play defense legally and moving towards the opponent at the time of contact is not legal defense.

Now, if B1 was going to completely and clearly miss A1 and A1 goes out of their way to make sure there is contact, we have a different story.