I'll chime in here on this. What SHOULD have happened:
Ref A (baseline one who blew the whistle to kill the play) and Ref B (one who made this brutal call).....................
In a 3-person crew, A is only responsible for the area in the key. He is not looking by where B is standing. HOWEVER..............................he KNOWS when he blew his whistle what play was like. He KNEW what happened was well after his whistle. And really B should have, too because the officials all have something attached to them that notifies them when the clock expires and when a whistle blows. Even if the latter did not happen, I promise you A knows this all took place AFTER he blew his whistle.
If this was me, and I was A, I get together with B (and C) and we discuss things. I let B know I blew the whistle well before the 3 as attempted. I have to let B know the play was dead and the 3 point try was "goofiness" and not to penalize it.
The failure of the officials to do this and come to the right call is disgraceful. But not shocking. I know NBA refs are supposedly the best ones out there but what we see is often far from what normally happens.
IF the ball was live Ref B made the right call. But it was not