[jsmeaton]

"Sir, please shut off your electronics device as it may interfere with the navigational systems."

"Um, no. Did you SEE that episode of myth busters?"

"Oh. Well.. um.. the real reason is so you pay attention".

You can't just change the reason because your original reason has been proven wrong. If this was the real reason, then they should have been upfront about it.

But like a sibling commenter states - reading a book (as opposed to a kindle), or being deaf (as opposed to wearing earphones - this one's probably a bad comparison..) carry the same 'risks' and neither are banned.