Timelords (as an alien species) have always been - in XXIst century Earth words - genderfluid/agender. Humans of 2017 (and mostly male ones) are upset to see a women in the role of the Doctor because it proves once again that gender is (mostly?) a social construct. Jodie Whittaker as the Doctor threatens patriarchy by its main roots: male superiority and gender binarity. Most of all, it threatens masculinity by taking away all its hegemonical strentghs and, even more, it makes masculinity look abstract, fragile, obsolete, at the opposite of what it wants to be since the beginning of patriarchy. That’s why it was a bold, necessary and pedagogic choice, that totally makes sense in the Dr Who Universe, and that’s also why it’s confusing/ frightening/ pissing off a lot of people.