Rule Clarification

[PIAA REF]

I have looked and looked and still am not satisfied, if you can point me where I would be very happy: The problem is that we have some officials calling a violation on rebounders during free-throws for simply putting their arm/hand into another lane space. On page 70 of the case book this action seems to be legal. I have talked to one of the guys and he swears that is is illegal to do this. Do any of you have any idea where he might be getting this information. I for one have never called a violation for players putting their arms over their spave and into anothers as long as there was no contact. Is there anywhere else besided page 70 of the case that may clarify this better?

Thanks