whether or not they have grounds for reinstatement, they will not be reinstated unless they apply for it. They then have to go though the process of meeting with the elders to prove they are repentant for running ahead of the organisation. It is not a matter of automatic reinstatement.
Imagine how a person feels who was d/f in the 70's for having an organ transplant when they read in the 80's that organ transplants are acceptable. They would not be automatically reinstated. They would have to show the elders that look on the WTS as Gods Organisation.
D/f is not for the sin but for the lack of repentance. If you do or believe something that later becomes correct that is irrelevant. You still need to repent for disobeying the WTS.