Correctable Error Question

[PIAA REF]

I don't understand the rational behind the first Case book situation. (Pretty sure it is the first)

Basically it goes like this, A1 is fouled, Is awarded a 1-1 but should have had a 2 shot foul, Misses the first shot and the ball is rebounded by B then passed to the division line to B2. Then the error is discovered.
Ruling is to go back and shoot the free throw with players on the line because there was no change in possession. Doesn't B get penalized in this case. What if the shot is missed and rebounded by A? To me it should be A has 1 free throw with laned cleared then B's ball at the division line.

What say you?