Being in the industry, this is a REALLY REALLY bad idea. Refining margins are next to nill. They'd not only need to figure out how to run the refinery as efficiently as possible, which is hard enough for a refining company like Valero, but for execs that barely know how to run their own airline, how are they going to be counted on to run this business properly?
Secondly, this is an old refinery. They would have to deal with the environmental nightmares of upgrading/running one of these things in the northeast. And, when this venture inevitably fails, good luck finding someone to unload it to. Delta will then get stuck with the environmental liability and the lawsuits that are come with the territory. Oil companies won't permanently shut down refineries in many places even though they're old and outdated because doing so would require them to dismantle and clean-up their toxic sites at costs Delta can't even begin to imagine paying for. This could be precisely the reason JPMC won't buy the darn thing themselves.