If it is accurate that there are Airlines out there where it is not unusual for someone to be on their mobile while the aircraft is in motion ( PF or PM doesn't matter) then something needs to be done to regain an appropriate culture within those Airlines.
I would be fully supported by my company for standing down an F/O that did that at my next port of call. If the companies are not providing that level of support it puts the Captains in a tight spot. From my cushy well supported place within the industry I still think it is the Pin C's responsibility to the passengers to not allow this behaviour though.....they aren't being paid to serve at a coffee shop so why are they behaving like that.....actually........are they being paid similar wages? Is that the root of the problem?