Sorry to hear they did that, pretty poor move on their part and doesn't give any sense of loyalty to their employees. It doesn't cost them anything to hold the CJOs that were offered, wonder why they did. Even if it's two years, it's still the same person they wanted before, just make sure nothing negative has come up that might need explaining.
If they did hold on to the CJOs then you're creating trust and loyalty, both to/from the company/employee. But by getting rid of it you're destroying any loyalty those people may have had, giving yourself bad publicity, and potentially really screwing people over.
I know it was stated that some people gave proper notice to their former employer anticipating a class date at Southwest. Old company wouldn't take them back at that point, Southwest just kicked them to the curb in the future, not a good position to be in. Or for those that are coming from Compass or Trans States, no going back for any of us, our jobs are gone regardless.
I certainly hope everyone else honors their CJOs, and not simply because I'm waiting on my class date.