No, I don't buy it. The point is, people are flying anyway during peak travel time. If they are taking that trip anyway, you haven't gained anything by "convincing" them to fly in summer. They were going to fly in summer no matter what.

AA would probably make more incremental revenue by convincing people to take an extra trip that they wouldn't otherwise have taken, during a non-peak time (since the plane won't be full). Convincing more people to fly during peak times is useless. Your planes are already full, and competition means that you only get a tiny part of of the extra revenue that comes from the extra demand (while the person using the SWU has to fly AA, no one else does, so your fares still need to be in line with the competition)