As others have said, the idea of this thread was how to manage passengers who are disregarding the rules/instructions, not whether those rules are indeed relevant in this day and age.
When the CC say to turn off your PDA, that means you turn it off, whether or not you think it is justified.
As a passenger, what can you do? Probably not much. If within a close range you could politely ask the other passenger to turn it off. If they refuse, then if you have the opportunity you could quietly mention it to the CC... but if they pull it out on the takeoff roll there isn't a lot you can do except for wait and maybe mention it to the crew so they can look out for if they try to do it on landing as well.
It is amazing how many passengers will directly disobey an order from a CC member, and it is upto the crew to difuse the situation (which is where the best crew excel... the ability to turn a potential standoff situation into one where the passenger thinks they have won, but the CC have achieved what they want). If they continuously ignore important directions, we can always have the authorities waiting for them on arrival...
