Given the App Store antitrust lawsuit and "big bully" PR issue that Apple is facing, they probably realize that now would be a terrible timing for them to flex

Given the App Store antitrust lawsuit and "big bully" PR issue that Apple is facing, they probably realize that now would be a terrible timing for them to flex their muscles and crush a multi-billion dollar ecosystem (even if it's the ethical thing to do). Facebook's concern isn't oriented around their revenue - it's about the 3rd party advertising ecosystem on mobile in general ($2B of FB's $80B revenue). FB and Google will take a small hit from their 3rd party mobile ad networks going away, but they still have their dominant 1st party businesses to fall back on. Who this really hurts are the apps that don't directly sell their own ads and rely on a 3rd party network to monetize. Those apps' revenues will be chopped in half overnight, sending a shockwave throughout the entire mobile ecosystem. FB and Google get poked in one eye, but most ad-supported apps will be blinded.