A type I once flew not so long ago had a spate of spurious fire warnings. Lots of dead puppy dogs and pussy cats as a result of the checklist item to gas them with halon.
It turned out mobile phones left on and packed in checked in luggage was the culprit.
So yes, they can have an effect, and in systems you wouldn’t think they would.
I just hate the arrogance of these plonkers that insist they know more about the effect of their mobile phone than the engineers that built their phone, the aeroplane they’re flying in, the airline they’re flying with, and the crew getting their sorry ass from A to B.
I guess they’re experts based on their BA in Art History.
Just do as you’re bloody told. If you don’t like it, don’t fly.