With respect, you left out the next paragraph from your quote, which shows that in the case of airlines, it would indeed be unlawful:

> However, there is no possible justification for differences in access to goods or services for customers from different EU countries in the following three situations:

> sale of goods without physical delivery – for example, if you buy something online that you will collect from a shop, rather than have it delivered to your home

> sale of electronically supplied services (excluding copyright protected content) – such as cloud computing services, or website hosting

> sale of services provided in a specific location – for example hotel bookings, car hire, tickets for entry to theme parks