The flight is not until next May so things could change anyway. If they say its legal then there is something that is not making sense. A simple solution is just to do the trip. If they fail to make the connection, they have to accommodate you on the next available flight. Check the schedule to see what is offered. In any case, I'd wait. My guess is that they are expecting another schedule change.
This is the method I'd use, unless I absolutely had to be somewhere the next day.
Keep on the lookout for a better fare, and if you find something, put it on hold and then go cancel the Expedia itinerary.
Keep trying with supervisors and Chris Elliott in the meantime, but unless you have an inflexible schedule on the return, I'd take my chances just waiting, misconnecting, and letting them take care of me. Heck, you could probably get a few extra compensation miles for your dissatisfaction of the way they handled this after the fact.