The PFC is a variable amount set by the airport, as pointed out MEM has none and I believe CVG is less than the current maximum. What does DL have to gain by opposing this? Assuming ATL will raise to $7 and CLT or another competing hub doesn't wouldn't that just impact the habits of the bottom dollar traveller Delta is trying to avoid? It seems Delta thins the less loyal customers and in theory gets a nicer home airport.