Assumption is the problem
The law said nothing about NB.
So why write policy which uses the words NB or GNC or GF.
That is a choice of the staff involved.
Part of the problem is the idea of "being inclusive of.... " and working in a regulated industry where the regulation has not yet rolled down to the staff level.
If GR = obligations and consequence the staff would want to limit the number of people within the PC and/or use very clear language to establish where their duty starts and stops. And as you say they would seek legal advice.
The questions asked would be based on the Equality Acts own terms.
And NB etc would be managed under "is proposing to undergo" but its again issue of benchmarking the appropiate group. If the staff are not sure the benchmark should be all of non-PC group create the control. Problems began when the benchmark was set as of the other sex.
The Courts said that there are 2 groups and each benchmark for controls is set as of the same sex.
And as you say a presupposes understanding of the equality law framework etc
Take this gem...
https://www.mumsnet.com/talk/womens_rights/5386944-i-need-help-taking-a-complaint-further?page=1
On your question about why the Council ask questions about ......., and why it is relevant, as part of the Public Sector Equality Duty, The City of Wolverhampton Council has a responsibility to ensure that we do not unfairly discriminate in the services we currently provide, or plan to provide.
Therefore, by asking equality monitoring questions as part of our consultations, we can break down the responses we receive and assess whether any protected characteristics will be unfairly treated because of the proposal being consulted on and plan suitable adjustments accordingly.
The Equality Act 2010 recognises ....
On your question on why the Council does not ask questions about pregnancy or maternity, the council aligns our equality monitoring questions with the Census 2021, where the only question relating to maternity was an employment-based question which wouldn’t be relevant for the Council to ask as we do not gather data on employment as part of our equality monitoring questions on consultations.