The point is that the captain is in sole charge of his aircraft. We may all have opinions of what's electronically safe but that doesn't cut any ice whatsoever in this situation. Some think they have a right to smoke; some want to get drunk; some want to use phones. So what? Is everybody is free to do his own thing? I think not!
If the crew says it's OK, then fine, go ahead. But if the crew says switch it off, you switch it off. It's that simple and if you choose to ignore crew warnings, then when you get caught, I trust you will get slung off, fined and banned.
There are hundreds of lives at stake and rules, right or wrong, are made for the safety of all.