My doubt arises as to whether the x-ray scanner can read the phrase seed, or whether an agent suspicious of the strange object could check it and read the words (even worse if he were to photograph it)
X-ray scanners at airports can see through a bunch of stuff - they can penetrate through a few centimeters of steel no problem, and their resolution is crazy too - they can make out little threads just 0.1 mm thick. But the real magic is in the software behind it all. It processes the scans and makes a color picture instead of just a regular black and white X-ray scans.
This helps the person watching the monitor identify different materials and objects inside people's bags. But they are not designed to decipher inscriptions engraved on metal plates. Therefore, there is no danger that someone will steal your coins that way.
However, while X-ray scanners might not be the biggest concern, carrying your seed phrase in your luggage remains a risky strategy. Airport security can rifle through checked bags, potentially exposing your sensitive wallet information to prying eyes or surveillance cameras. And with airlines' unreliable luggage tracking systems, lost bags or misdelivered suitcases could hand your precious seed phrase over to a complete stranger. There are simply too many potential vulnerabilities to consider and when securing your crypto assets, limiting access points by keeping your seed phrase far from airports and transit hubs proves the safest bet.
Still, I don't think it should be a problem even if it is carried about, because I know seed phrases could just be plain words that may not mean anything to someone who knows nothing about it, only if of course one makes it obvious.
This is not something you should bet on when it comes to the security of your crypto assets.