Is there a 'more innocent' explanation for this, that the lead up to 2010 was within the timeframe following the law-change (in mid-2000s?) that was based on the idea that there were only about 5,000 transgender people who would want a GRC?
So the sex / gender cover-up may have been along the lines of 'gender is the correct term, if we're being precise and pedantic about it but we're talking about so few people, who have all had their bits chopped off and the frequency of those people staying as hospital inpatients will be so low, that this really isn't a detail we need to bring to people's attention, so causing unnecessary confusion.'
Or, maybe it was Tory cronies seeking profits for their big pharma friends (and the shareholding, non-exec selves), who were probably already some years into development of drugs to support a transhuman future.
Plus, it was entirely possible to address the issues and recognise the problem in principle, even if, at that time, there were few people with GRCs and no idea of self-ID.
Cock-up or conspiracy?