That's because the issue of men vs women in programming really is an all-or-nothing topic. Either you believe that a female is capable of being an equivalently skilled programmer to a male, or you don't.
Referencing biological differences always cascades to a question about the innate ability of a female to program. The best example I can point to is the infamous internal Google manifesto on male vs female programmers. If you read that text, it appears reasonable enough: the author thinks that there are biological differences, and these differences might lead to differences in programming strengths. But it is a wolf in sheep's clothing; as soon as you believe that there are differences, it follows that one set of differences must be advantageous to the other.
I can understand that there are biological differences between females and males, but I absolutely and vehemently choose to believe that there is no inherent difference in ability - females are 100% as capable as males when it comes to programming. Full stop.
Yes, this is double think. But I'd rather be a hypocrite than hold a secret belief that my biological sex makes me a better engineer.