Throw-in Scenario

[Remington]

Heard of this play in South Dakota last weekend and wondering everyone's thoughts.

After a basket by team B, A1 has a throw-in where he passes the ball to A2 who runs out of bounds on the end-line to receive the pass. As A2 gets out of bounds he is fouled by B2 just prior to receiving the pass from A2.

The officials called a Technical Foul on the play (there hadn't been any previous DOG warnings). I was asked about it and couldn't find the exact play in the case book and piecing it together I have come up with a DOG warning for breaking the plane and a common foul as A2 was not the thrower yet. What are your thoughts?