Maybe ... by making an explicit enumeration rather than saying something like 'and any other non-elective conditions' or similar language to capture the central

Maybe ... by making an explicit enumeration rather than saying something like 'and any other non-elective conditions' or similar language to capture the central idea, it seems that there were specific areas where they saw problematic discrimination and chose to make them illegal. And the concepts in question were known at the time, but generally not considered "acceptable" by sizable portions of the population. Speculating, of course, but if they had added language about sexual orientation at the time it would likely have met considerable resistance. As it was the original text didn't even include "sex"; that was added as an amendment in committee. As far as I'm aware there were no attempts to correct the bill in the other direction, by excluding gender identity or sexual orientation explicitly from the list; which I think can be reasonably interpreted to mean that the commonly held view is that those were not included. At least now, any members of congress who disapprove of this action by the courts is left to decide whether they do accept those protections or not, and hopefully one of the bills explicitly adding that text will move forward so that this decision can be made moot by the legistlature.