The people in F that pay cold hard cash IMO expect a level of privacy
Apart from the captain, who did and didn't pay for their seat? If the 2 year old that had her seat paid for by her dad screamed for half of the journey, is that better or worse than someone from economy sharing a meal up the front that you may or may not even know of? An economy pax asking to sit for a meal in F is a bit different to being asked the other way round.
Regards,
Michael