Originally Posted by Dave Noble

When you buy a ticket for a flight in a particular class, that is what you are buying ; there is no entitlement to swap around passengers between classes of service

If the person had asked in advance whether it would be ok to swap , the attendant would either have said yes or no - if asked in advance, the attendant's response might have been different or may have still have said no

Either way, it would have avoided the situation that the passenger created