Just a couple of months ago, someone was still suing[1] to block Alaska Air/Hawaiian. This is a merger that already entirely went through. I would predict equal likelihood of some state lawsuit derailing a merger like this.
Nevertheless, I have very little faith in states somehow blocking big mergers. Can you cite an example where this has happened? We've had basically every airline, several supermarket chains, and every major media company go through 1-2 rounds of megamergers. Which, specifically, have been successfully blocked by states?
In 2017, Valero tried to acquire some energy infrastructure owned by Plains All American. The FTC cleared it but California's AG filed to block the deal, which was ultimately abandoned before the trial could begin.
Considering that California is one of the states and it’s Warner Brothers and Paramount, both entertainment companies based in California, the bark has a lot of bite.