I get what you are saying, one has to read between the lines a little, but if you read carefully I think that is what is implied:
"Albert Einstein called her the most “significant” and “creative” female mathematician of all time, and others of her contemporaries were inclined to drop the modification by sex."
If you drop the female from that sentence then it reads "most significant and creative mathematician of all time."
Another point that, which I think you pointed out as well, was that this is a misquote of Einstein. The original statement included the clause 'since the education of women...' which would make the dropping of gender much more reasonable.
"Albert Einstein called her the most “significant” and “creative” female mathematician of all time, and others of her contemporaries were inclined to drop the modification by sex."
If you drop the female from that sentence then it reads "most significant and creative mathematician of all time."
Another point that, which I think you pointed out as well, was that this is a misquote of Einstein. The original statement included the clause 'since the education of women...' which would make the dropping of gender much more reasonable.