The SC had to decide whether a GRC holder should be treated as either their birth sex or their recognised gender.
I'm reluctant to push the point further, because it requires me to argue from the perspective that Labour isn't that incompetent, stupid, craven, etc., but the SC did consider whether someone could be both a woman (by dint of biology) and man (by dint of GRC), or vice versa, and they deemed the result logically incoherent. That incoherence can't just be gotten rid of by adding a couple of words to the act, i.e. it's important to recognise that in the judgement 'parliamentary intent' is not just what the legislators might have thought in their individual minds, but the logical system they set forth in law, as a whole.
The situation could be resolved if Paliament decided to take on those issues like maternity, board makeup, athletic participation, one by one or created some framework and guiding principle for resolving logical conflicts, but that is not an easy legislative task - I just can't imagine a scenario were Labour would think they could prepare it in secret and submit it for vote without a gigantic political firestorm and collapse of the legislation.
I too (unfortunately) can't 100% put it past Labour to try - Parliament after all is allowed to legislate anything it wants- but I think it's probabilistically unlikely because the SC made it plain that their decision was not just based on the fact that the EA 2010 didn't set out the explicit language, but instead because the situation that conflating the two would create is logically untenable.