C5 is not used for line-ups, only C6 is for intersection departures on 07R.
The stopbar for C6 is quite a ways away from the RWY, and the final part of the RWY entry is rather steeply uphill (relatively speaking). As such, line-up time is rather unpredictable, and lining up an aircraft only after the landing aircraft has passed leads to a very long time of nothing happening, and the next arrival only coming closer and closer.
Several runway holding positions are used (Hotel, 1 and 2, visible on charts in the AIP). Using runway configuration 01/07 results in a very busy environment for everybody involved, both on the flight deck and outside.
Mistakes happen, we're all human, key point is to learn from them, which seems to have happened.