From a purely strategical perspective I think Facebook probably did the calculus and realized that the negative press of not running her ads would far outweigh

From a purely strategical perspective I think Facebook probably did the calculus and realized that the negative press of not running her ads would far outweigh the damage it could do to her campaign. There's a good chance that Warren would have taken them to court, she wouldn't have had a case, and she would have known that, but the publicity for her platform would have totally been worth it. If I was Facebook I'd be essentially "playing dead" with respect to Warren, her entire strategy depends upon positioning herself as David, battling against Facebook's Goliath, for the good of the country. It's a good strategy, people will respond to that story-line, but only if it's interesting, which requires Facebook and the rest of FAANG to fight back, if it's just Warren shouting into the void it'll be boring. Eventually they'll have to respond, but if she doesn't get enough traction with the story he candidacy might be derailed before they have to and it'll all go away.