A quick look on ITA for this evening shows
* Direct on US Airways
* one stops via BWI, EWR, JFK, BOS, DTW, BOS, and more.
* I find it hard to believe there wasn't a single WTP or better seat going from anywhere on the north-east seaboard that night

Only one of the domestics is on AA though.

There are at least connections onto BA214, BA188, BA292, BA212 and BA228, without having to know anything about U.S. geography.

Don't tell me that all domestic flights out of PHL were full (aside from ORD), and that all these BA flights were full.

There's also a direct flight on US Airways too, however again WTP should map to Business in that situation.

Customer service is suppose to service the customer, bring these options, and present the customer with the choice.

Therefore either BA staff don't have access to ITA to see the myriad of options, or BA have made a commercial decision not to reroute stranded passengers on other airlines for domestic legs.