The decision seems to have been made around 10 pm last night. At that point many long hauls will have been already airborne. I suppose it’s possible someone was rejected for the latest departures yesterday, although I haven’t seen that confirmed.
No one will be rejected at LAX today since that flight arrives tomorrow.
Captain on KL1932 claimed that KLM would offer to ship luggage on a routing not via AMS while the passenger flies as booked. But this was shot down immediately by a passenger sat near me who had this option rejected both in phone conversations with KLM and at checkin.