The odd thesis here seems to be that the lufthansa flight has to bear the entire burden of the delay. Eventually there will be a gap when you have runway space free. Rather than shove the lufthansa flight in right away, then cause every further flight to be delayed until that gap appears, lufthansa has to wait for the gap themselves. "No visual approaches" is treated as a sort of deviance which the ATC won't allow the effects of it to cascade to anyone but lufthansa. This added context makes it clearer exactly what the OP article is criticizing: the ATC had the complete ability to let the lufthansa flight land whenever they liked, but was choosing not to, and there are certain negative effects which that choice could have.
