I don't really have anything nice to say about TSA. We have been on many flights both domestic and international with our bikes the last 5 years and TSA has opened our bike cases each and every time. The very first time they did so, when they repacked the bike, they managed to get the dropout wedged in an unprotected part of the case between foam and it got bent. The frame was a steel frame without a replaceable dropout, so I had to go through considerable gyrations to get the bike fixed to ride. Subsequent to that, we pack the crap out of the bikes and *only* put bikes into the bike case - or in your case, the box. Keep it simple - TSA has enough problems with that. You need to make your packaging idiot resistant. FWIW, I'm also on Delta a lot and I travel a lot.

My suggestion:

1. You will need to get something to put in the dropouts of the fork and the rear frame. That's where you can do real damage if they crush the frame from the side. Frames are super strong, but only if you protect the dropouts from being crushed.
2. Remove the RD and pad it. See the next couple of steps below.
3. If you can, remove the rear dropout AND have a spare. There are things you can get from your LBS that fit in this and is how they ship the bike. If you can't remove the dropout, then cut a piece of PVC pipe the length of your thru-axle and put that between the dropouts with the thru axle inserted (that's what we do). Do the same on the fork.
4. Protect the rear triangle with one of these protectors from SCION. You can take the RD and pad it and stuff it in the frame in this thing and it will be seriously protected and it will do a lot to protect the rear end of your frame if they toss the case/box and it lands on that corner. I don't take the chain off, I just make sure it's out of the way and strapped down.
5. I'd also get one of the various foam kit to protect the frame. They're reusable and worth it. Stops damage to components from rubbing. We use the one from Orucase and have for years.
6. We've found it to be really important to only put the bike in the bike case. If there is more stuff and it's kind of a puzzle to put it back together, you're going to exceed the capability of an impatient TSA agent. I bet they hate seeing bikes.
7. Remove rotors and pack them in cardboard inside of some Amazon foam envelopes.

We've done more than 25 segments this way in the last 5 years (all Delta/KLM/SAS) and nothing has been hurt. That said, I do carry some spare parts just in case - seat post collar for my wife's bike, a spare headset so if they ding the top or bottom during shipment, and extra RD hangers for both our bikes.

Agree with this 100%. TSA are not your friends.