Firstly, has the councillor quoted chapter and verse on the breach of equality law? If the council made a decision, all members must abide by the decision. If the councillor is able to demonstrate that the process by which the decision was made was flawed, they may ask for the issue to be reviewed at the next meeting. From what you have said, this appears unlikely.
Councillors can, and in my opinion should, seek clarification from the clerk regarding such procedural matters if they have concerns. Sometimes this encourages the clerk to carry out the necessary checks and serves as a learning process for all concerned.