Penalty for this or not?

[Illini_Ref]

This has been discussed somewhat in other threads.

I worked with a very good rules guy last night and we differed when discussign a hypothetical situation. Here goes.

A1 inbounding on a SPOT throw-in. B1 defending the thrower. A1 is well behind the line and releases the throw. B1 reaches through the plane after the ball is released and touches the pass (or grabs it).

I say there is no rule making this illegal. The rule speaks of a ball being passed outside the line to a teammate (not a spot throw-in) and reaching through BEFORE the ball is released. He was certain that this was a violation.

Can anyone answer with certainty?