In this case the crew/ company took the correct option.
By turning back the crew had the option of gliding, in case of total engine failure however remote. A suitable airport either civil or military, from 30000 feet over europe there is nearly always an airport of more than 6000ft long within gliding distance.
If the flight had kept on track to sin it would have flown over high ground in Turkey Iran Afganistan/Pakistan. Areas with very few airports/support.
On the Ba flight which lost an engine after t/o it flew over north america with many airports available. Crossing the atlantic at least 1900 nm overwater it had very few airports /options available.