Ultimately this is long on narrative, and in the near-term relies mostly on buying carbon offsets which are questionable in effectiveness and limited in supply (if every company wanted to fully offset there wouldn’t be nearly enough opportunity to go around, so Delta is in some sense just bidding up the price of offsets that will be taking place anyway).
Noble goals, and surely they’ll make progress towards those goals, but the claim that they’ll be a carbon neutral airline next month is dubious to say the least.