Where does the next throw-in take place?

[Adam]

Wait a second? This is an endline throwin, as in A had the right to run the line? Let me get this straight.

A1 grabs the ball and heads out of bounds after a made basket, presumably to throw the ball in. He throws the ball to teammate, A2, who is also standing out of bounds.

This is a legal play. A2's only requirement is to either be in bounds or out of bounds. If he's out of bounds, his foot can be on the line and he remains out of bounds. Still legal, no violation.

Why are you calling this a violation?