Confusingly I think this means that you can only use wireless headphones with the 'provided entertainment' when the flight has Wifi because that's how they get

Confusingly I think this means that you can only use wireless headphones with the 'provided entertainment' when the flight has Wifi because that's how they get their entertainment to your device. If the flight doesn't have wifi you have to use the in seat entertainment system and therefore can't use wireless headphones (because the entertainment system doesn't support them) not because you're not allowed to have them enabled.