In badminton, how do invasion and obstruct interact chronologically?

This question is somewhat theoretical in nature since I’ve never seen it actually happen, but I just saw an instance that came very, very close, and I wondered what would have been done if it had actually happened.

Section 13 of the Laws of Badminton deals with faults and among other things specifies that:

13.4 [It shall be a ‘fault’] if, in play, a player:

13.4.2 invades an opponent’s court over the net with racquet or person except that the striker may follow the shuttle over the net with the racquet in the course of a stroke after the initial point of contact with the shuttle is on the striker’s side of the net;

13.4.4 obstructs an opponent, i.e. prevents an opponent from making a legal stroke where the shuttle is followed over the net;

Now these two can easily interact with each other since they occur in the same situation: when a player is making a stroke where the racquet goes over the net and ends up on the opponent’s court, while the opponent has his racquet up in defence to try to catch the shuttle.

Consider now the following scenario:

• Player A has an opportunity to take the shuttle very close to the net and smash/tap it down on the opponent’s court
• Player B sees this and puts his racquet up in defence to hopefully intercept the smash/tap and get it back over the net
• Player A smashes/taps the shuttle, but the shuttle ends up not crossing the net, so Player A strikes the shuttle on his opponent’s court
• Player B’s racquet is positioned in such a way that it completely unambiguously obstructs Player A’s racquet in the completion of the stroke

In this situation, Player B put up his racquet in position at the net before Player A had started the stroke, and thus also before Player A commits the fault of striking the shuttle on his opponent’s court.

But the actual obstruction that prevents the completion of “following the shuttle over the net with the racquet” does not occur until after Player A has committed a fault – a fault which, incidentally, puts 13.4.2 out of play (since the stroke is no longer “after the initial point of contact with the shuttle is on the striker’s side of the net”).

So it all boils down to which exact moment in time a fault is taken to occur according to §13.4.4:

1. as soon as Player B raises his racquet to the net, knowing that Player A will almost certainly try to smash/tap = Player B commits a fault before Player A, so Player A will get the point despite hitting the shuttle on Player B’s court
2. when Player A’s movement is actively impeded by Player B’s racquet = Player A commits a fault before Player B, so Player B will get the point despite obstructing Player A’s stroke.

Which scenario would be followed if it happened in an actual match?

Or would the umpire likely just consider it too close to call (the difference is milliseconds) and play a let?