Wether or not you have a rating as a S/O is a bit of a detail. If it is in your logbook (either as P2 or P2X), it doesn't really matter. It is up to any prospective airline wether they actually recognise the time or not. You can have the rating with lots of S/O hours, but an airline may not necessarily count those hours towards their qualification requirements. if the CX guys can at least put some hours in the logbook, that is Ok to some airlines. They are still official hours.
Of course the next debate becomes - "Do you log seat hours or total sector hours?" i.e. some airlines/pilots log hours that they are in the bunk.