Force Majeure is not just a "thing" anyone can throw down on the table at any time.

Have you read AA's contract with OO? Or the others? Force Majeure only applies if you're stupid enough to allow it in your contract. Those managers are not nearly as dumb as regional unions, their contracts do not resemble the swiss cheese typical of pilot contracts in any way shape or form. Plus the regional managers learned a few lessons over the last couple decades when UAL decided to try and exploit weak language.

I'll 100% guarantee you that it's not that easy. And COVID is not even a clear-cut Force Majeure, so even if they thought they might make it stick, it WILL get litigated and they might very well lose. Just a SWAG but I'd say only about 30%-40% chance of Force Majeure succeeding in litigation. The virus may have been an act of God but it didn't ground airplanes.

A clear Force Majeure would be something which physically prevents airplanes from flying (tsunami wipes out hub, Fed grounds all traffic ala 9/11). Bad economic circumstances are less likely to qualify, regardless of cause because that's second, third, fourth order effect, etc. At some point everything bad can be traced back to a butterfly flapping it's wings in the amazon (or some dude in asia eating raw pangolin butts).

If they need to shut something down, safest bet would be WO's because they can't sue mainline. Sometimes "WO" means PWNED, and this might be one of those times.