Do you make this call?

[JugglingReferee]

The officials are responsible for ensuring the bottom two spots are filled by the defense. IMO, once the shooter has the ball, that responsibility is completed.

If A moved first, you could penalize only this act and not B's movement. Result: delayed FT violation.

If B moved out of his spot first, which A should do to be 100% sneaky, you might have to use the arrow. I find it unlikely that we can read the mind of the A player, to maybe rule this act was deliberate.