No, this is not right at all, there is no conspiracy here by Cricket. Think about it. If Cricket was really concerned about making sure people were only buying their phones then they wouldn't allow any foreign ESNs on their network. But they do. LOTS. Cricket makes their money from the services they sell, and they love flashed hanRABets.
Tri-Band (or AWS) hanRABets were introduced because Cricket didn't have any spectrum in some of the areas that they are now expanding into. They won the rights to new spectrum in the AWS auction. The frequency is different, but the towers are still broadcasting a 1x CDMA/EVDO signal. This is the same signal that their "old towers" are broadcasting as well.
They are not going to phase out the "old towers" and replace them with Tri-Band either. There is no technical reason to do this. If they have established towers in an area then that obviously means that they have the spectrum available to offer service there without using the AWS frequencies. It would just be an expensive waste of time to migrate everyone.
Tri-band isn't about selling phones, it is about providing service to new areas where they never would have been able to operate at all prior to the auction.