b) if it was never the intention to excommunicate Group A then the "consensus decision" must also now be invalidated (as moving forward will result in the proscription of Group A), and the global network needs to work quickly to establish the Mayday collective as a new IMC.
I believe that either of the above options calls into question the validity of the decision reached in Bradford.
A fork signifies - by the very image suggested by the implement if nothing else - that two projects would go forward. A fork without two halves is merely a spike, to labour the metaphor.
1 of Sheffield IMC