This has made me really angry: an explicit dismissal of one of the protected characteristics that subsumes it into another with which it, arguably, conflicts. I'd say this is grounds for complaint, although whether or not you want to go there is another matter entirely! But the arrogance of
"sex... is less useful as a frame of reference for understanding and discussing human behaviour and experience than gender"
is astonishing. I think the word "privilege" is too liberally, carelessly and sometimes cynically used (and abused) nowadays, but this is something that I find it hard to imagine a woman writing.
I'd be tempted to reply...
Dear...
I was concerned to read your assertion that "sex... is less useful as a frame of reference for understanding and discussing human behaviour and experience than gender". In the light of this, I am writing to seek your assurances that our company remains committed to the letter and spirit of the Equality Act 2010, and associated values.
In summary, your email appears to privilege one legally protected characteristic ("gender [reassignment]") over another ("sex"). This seems incompatible with the Equality Act [quote from Act if possible - don't know it well enough?], which establishes that no single protected characteristic takes precedence over, or subsumes, another. I would be grateful if you would clarify company policy on this.
If the intention of your email was, rather, to make a distinction between legally protected characteristics (which the company upholds), and a "frame of reference" (which it applies), I'd appreciate clarification on the following points: firstly, how privileging a "[more useful] frame of reference" for assessing "behaviour and experience" can be reconciled with the Equality Act; secondly, how such a "frame of reference" would be applied in practice.
Lastly, I would appreciate your assurances that the company recognises that the interrelationship of sex and gender is a complex political issue, and refrains from partisanship. For many of your female employees, the assertion that gender is "more useful" overall will be difficult to reconcile withtheir own lived experience of, for example, periods, pregnancy, breast-feeding, maternity leave, abortion, endometriosis, menopause, and greater physical vulnerability to rapeand domestic violence. There is ample statistical evidence in support of this perspective. I would be grateful if you could clarify that you recognise its validity, and such employees will not be negatively impacted by your recent statement.
Best wishes,
...