What I believe happened....
Waley wanted to release Freddy before training camp all along, but Pegula told Doug to keep him on and to allow Jackson to prove him wrong... Problem, jackson played great against Pittsburgh, but Waley was planning on cutting him all along.
In the end Waley doesn't have a reason for keeping Jackson on the team through the preseason other than the owner made him... It would have been a better for all parties if they had parted ways before camp, but Waley was handcuffed. There's no doubt that Whaley told Jackson (which was a lie) that he will make the team if he wins the rb back-up competition. What was he supposed to tell him? The owner is making me keep you on, but I'm definitly going to cut you in the end because we would rather keep our younger plethora of running backs?
I see this blunder on Pegula. He's a new owner, he needed to either give Waley full control of the situation to cut Jackson prior to camp.... Or he can be an Al Davis and have told Waley that Jackson stays no matter what. He went for something in the middle and it now looks bad for everyone.