That's such an edge case though.... what about my fine tuned piano? Or my aquarium? At some point personal luxuries don't have to be accommodated for
Privileged enough to fly somewhere specifically to ride bicycles? C'mon, I think you can find a good enough bike to rent when you get there.
I've also done it the other way, my main bike has S&S coupling so I could bring it aboard the Eurostar. For touring I prefer my own bike, because I have the racks set up for my panniers, but when I do that, I prefer travelling by ferry/train.