It means excessively obvious. The idea that women are treated worse than men is profoundly demonstrated. A woman who wants independence from a man is denied on the same day a man who admitted to drugging and raping women goes free. Either of those examples stresses the point. Both together is excessive. "On the nose" means exact or accurate. "Too on the nose" is exact to the point of absurdity.

"Too on the nose" is also partly a reference to being punched in the face. So to be "too on the nose" or you might hear "a slap on the face" - in this context it figuratively means that whatever has happened is obviously very insulting.