I didn't say it was profitable, I said it has to be more profitable than flying head to head with SWA to STL and MCI for whatever crazy fare that SWA chooses to fly that route as DfW People has reported. Being the only non-stop to PVD from DfW, AA could charge a premium for this service to ensure profitability.
To answer your question, no it wouldn't make sense to add more than a single non-stop when the majority of your passengers are business travelers flying. Being the flight times are perfect for conducting business in both PVD and DFW, an added flight during the day would most likely only attract money losing passengers and not business travelers. I don't subscribe to the theory of throwing more seats at a market just because one flight goes out full daily unless of course we are tracking potential bookings or denied bookings because of lack of seats.