It is not really profit in the sense of being a motivation for action. It is a reward for past action. In a proper image of the pure market economy, there is no tendency toward equilibrium in the long run. The usual distinction between short run and long run effects disregards innovating in order to focus on copying. Although this is a useful pedagogic tool, it should not be applied in isolation.
Innovation is always a characteristic of real entrepreneurial competition.
Since predatory pricing can only be achieved by an entrepreneur who has attained a position to charge a monopoly price, the profit gained as a result of predatory pricing is part of the reward for an earlier innovation. Accordingly, there are no grounds in the story for market intervention.