As Ray says in the last chapter of CoC, before 1981 DA was quite different from DF. "Persons who resigned were not treated the same as those disfellowshiped", they were not shunned for example, except when the DAd person enters into politics or military.
I put it on account of humbleness that Ray says he doesn't think they changed the policy just to use it against him, he probably feels he wasn't so significant as to warrant such a far-reaching change. But it seems way too convenient that the policy change came at that exact time, too much of a coincidence. Peter Gregorson DAd himself before the change was made, and zap, suddenly he finds himself shunned, and Ray questioned for associating with a DAd person. Sounds like a political plot to me...
This just goes to show the heartlessness of the GB, they only care about their position, they wanted Ray out, so they made the final step to turn the JW into the destructive cult we all love to hate. This single step is causing so many of us huge problems, with fading, losing family, friends, etc. If there was a clean way out I would only be half as angry at them. And all this just to get rid of one man?