And how much would that cost?
Better to pull the service earlier, when fewer passengers are effected, rather than do what some other carriers do and kill services 2 weeks before departure date.
If Primera are to make a success of the new T/A venture then they aren't going to be splashing the cash unnecessarily, nor persevere with a route that looked them (and only they have the figures) as though it may not be an overnight success.
Low cost operators don't have the luxury of 2 years to develop a route, which is why you see so many routes come and go after a season, or sometimes even less.