The judge should have ordered Meta to place a banner on FB so that everyone can see it and join if they're a victim.
Not likely to survive 1st Amendment challenge - it is possible to compel somebody to certain speech as a result of losing a case, but doing this as a prerequisite when the case has just started is not likely to fly. Otherwise I could force Facebook (or any other platform) to publish anything just by suing them - and anybody could sue anybody else on virtually any grounds.
Wow this is a really good idea. I wonder if the various state trials happening as well should use this for remediation too.
It's not a hard thing to implement on their end and should be mandated by a judge as you said.
Filing this away for later use.