My wife worked at Travelport in the late 2010s. They ran a lot of Delta’s systems but Delta of course has their own infrastructure. Some of the history of Delta’s teams is intertwined with the companies that were merged together to form Travelport.

From what I could tell from her talking about work it wasn’t particularly far off the state of the art at the time. They had a fancy new AWS hire to help lead them into AWS from mainframes. That didn’t fully work out but they still had a bunch of containerized .Net and Java running.

Mostly this whole back and forth argument sounds like a ball of pain with everyone upset at each other and very little of it mattering unless lawsuits are filed. If Delta is using Windows at IBM it doesn’t make them “ancient.”