Earlier quoted context omitted.
> "Contextually relevant!" That's a good one. :-) It's true on a global scale, not just in the Arabic context. As you immerse yourself in a language, you're encouraged to follow newspapers/articles/tv/shows/etc. It is entirely unreasonable to censor your own learning process. Take this unfortunately common headline: Death toll of Yemen anti-Houthi bomb blast rises to 49.[1] Now censor your knowledge: [? ?] of Yemen a…
You're not censoring your learning process by putting flash cards in your checked baggage and taking a book in your carry-on.
In other words: the flash cards are most useful to him in his carry-on so he can study while waiting for/during his flight. Putting them in his checked baggage (assuming he even checked a bag) would defeat the purpose.