Norwegians have this fanciful notion that all European and north American countries are essentially the same and that nothing is as bad as it’s made out to be by those hysterical foreigners. This requires some degree of cognitive dissonance because they also feel like there is no country as good as Norway and everyone must really want to be Norwegian.

So he probably assumed it wasn’t nearly as bad over there as people are saying and if he was to get into difficulty he could just say he’s Norwegian and people would just let him off because everyone loves Norwegians. Also he’s 21 so not terribly smart yet.

Not to mention that he’s probably never been in a situation where a border control person takes your phone.