Sadly, technically they are correct. However, their attitude is not conducive to good customer relations, something they desperately need in their present circumstances. Call back their reservations and ask to speak to a Supervisor. Explain the situation accepting that it is not their responsability and ask if there is absolutely nothing that can be done (in a semi-pleading voice). It'll probably get you nowhere, but hey it's worth a try, you might get connected to a sympathetic human being (rare breed in the airline reservation business these days). Good luck.
You could try the same with AA Eagle and see if they would rebook her on other flights (if there are any).