Breaking the plane by defense during throw in

[Damian]

NFHS Rules.
Rule 7 Section 6 Art 4 states that no opponent can cross the throw in boundry plane until the ball is released. At a clinic they are teaching that if a defender reaches thru plane after release and touches the ball its a technical foul.
Situation: A1 is the thrower on his baseline halfway between lane and 3 pt circle. A2 drives towards lane from opposite corner. B2 defending from inside lane bats ball out of bounds on pass from A1 to A2. To touch ball he reaches through boundry plane.