Player control/Blocking foul?

[GoodKolbeMan]

Pretty new at this, but this situation has been on my mind for awhile so I'll pose it to you vets:

To make it simple, let's say Team B is in a zone defense, 2-1-2, 1-2-2, etc. A1 with the ball is at the elbow defended by B1. B2 is in defensive position just under the glass, same side of lane. A1 gives B1 an excellent shot fake causing B1 to jump in the air to attempt to block the faked shot. B2 also taking A1's fake of a shot, turns and faces the glass to watch for a possible rebound. A1 drives past B1, so you can forget about him because he's still in the air. A1 goes in for a layup and essentially climbs up over B2's back to score a goal.

Now, if the contact is severe enough, would it be a player control foul or a blocking foul? In trying to understand Legal Guarding Position I've kinda read into the definition that a defender has to "either actively defend or get out of the way". So, if B2 turns his back to an approaching offensive player with the ball, is it fair? sporting? for the offensive player to go through B2? I'm thinking 'yes' because B2 is not in LGP, (he's not actively defending and he is 'in the way'), but it's these type collisions that get the parents, fans, coaches of Team B going nuts because A caused the contact. And, I'm not saying A1 barrels into him with intent to clobber him, A1 is going to the goal for a score. I think this is probably more a situation I see at lower levels where you have the 1 good player who has good skills and the big lug is under the hoop a couple of heartbeats behind the others.

What say you?