Look at the two situations. In the first situation, Team A can't score any points.
In the 2nd situation, since A1 has returned to floor before charging into B1, if his shot goes in, the points would count. Because of this, I would guess that the rules committee made this diferintiation.
I am sure that our resident historian, who probably has the original rule book to quote from when this rule was put into effect, will enlighten us on the situation.
