Backcourt?

[Rufus]

I believe the case play is illustrative only (i.e., here's one example of how the 9.9.3 exemption works) rather than exclusionary for any instance outside that in the casebook play.

The throw in ends when the passed ball touches or is touched by another player inbounds (A2 in your example), when the passed ball touches or is touched by another player out of bounds except as in 7.5.7, or the throw-in team commits a throw-in violation.

The throw-in in your example ended when A2 touched the ball in the air. The exemption in 9.9.3 ended at the same time. The only player the exemption could apply to is A2 therefore, if he passes the ball to A3 in A's backcourt, I think that would be a violation.