I don't know what is unclear about the words in bold print:

Convert Partner Points to Miles and then list a bunch of partners explcitly such as Club Rewards from Diner Club Internationa, Hyatt Gold Passport, Starwood Preferred Guest.....

Furthermore it says "Delta reserves the right to modify this list of elligible Skymiles partners during the promotion and any elligible partner change will be posted in these rules".

It does not say that Delta reseves the right to make those changes retroactive.