That'd be a tough one to prove, IMO, but IANAL
I seriously doubt that anybody wants them to get off scott free. I know that in a job like that of an airline pilot, awareness - not only to the sky around you but the instruments and functional mechanisms of the aircraft itself) are important. The issue is, and always has been IMO the punishment fitting the crime. Certainly you have to consider the nature of it, the previous record of the pilots in question, and just applying common sense instead this emotional bloodlust that ALWAYS comes up in issues like - and very different from - this.
IMO, they shouldn't get their licenses completely revoked as some people have said they should. That is the textbook definition of seeking bloodlust instead of actually addressing the issue. Fired? Maybe yes, being aware of your surroundings is important in being a pilot, paying attention to what is going on in the cockpit and the airspace is absolutely vital... not to mention that being late can cause issues with regards to connections and even other flights that are supposed to be coming in later that may be delayed from the extra time caused by this aircraft occupying this gate for longer than it should, ultimately costing Delta $$$ - something no airline has a lot of right now.
I wouldn't be surprised, if the pilot's story is true and they were reviewing company policies and scheduling software as I heard, tried to take Delta on claiming they created this situation by applying the pressure to quickly learn these new policies and whatnot. It could happen, I'm not saying whether or not I support that move.