Too bad it's complete poppycock. The suit takes a limited knowledge of fare buckets and married segment logic and tries to spin it into some grand conspiracy. They find T bucket availability and on MSY-SLC and SLC-SEA flights and then seem to believe that DL is tricking them by not allowing them to book a one-way T fare on MSY-SEA via SLC. It could be married segment logic or it could be that they did not meet the fare requirements for the T fare (advance purchase, roundtrip ticket, etc.). In either case, married segment logic is not illegal and has nothing to do with the Best Fare Guarantee. It's not like third parties can simply ignore the married segment logic and sell you a cheaper T fare for the MSY-SEA route than the fare Delta was offering. Sorry folks, there's no smoking gun here.
I disagree. I've found cheaper fares than on dl.com for the same flights. (I can't recall if it was the same fare class, but my ... is in the same seat whether I book in L or T so why should I care?)