Try being up the front end of an Airbus and explaining why the ILS has gone haywire, why one side is suggesting aircraft is on horizon and the other is climbing, and multiple false ECAM warnings. No explainations.
I have seen mobiles cause inteference to cabin IFE, as well as radio.
Who knows if it's just electronics going temperemental, or mobiles/ other electronic devices causing it. Either way, I'd rather be safe than sorry.