I will confess that I didn't recall the AR. But, when I went into the case book, I think, perhaps, we might have 2 different sitches.
If I read the original post correctly, B established LGP on a player
with the ball before falling.
A.R. 87 (this year's book) has the B falling before A gets the ball, therefore never establishing LGP on a player with the ball.
I'm sticking with my opinion (even if it's wrong
).