I would seriously argue that "closer to" in this context can mean multiple things. For, e.g., medical purposes Jenner is much nearer the male than the female cluster. [EDITED because I'd got things the wrong way around in the previous sentence.] For some others it's the other way around; e.g., the only pictures I've seen I would classify as nearer "typical female" than "typical male". For some others it's more complicated. For some others I simply have no idea (I have never met Jenner nor heard her[1] voice).

It seems to me that the great majority of the interactions people have with one another are ones where the impact of gender is (for those of us with the good fortune not to be hypersensitive to such things) rather small, and in those cases a definition that requires me to call a person a man even though the person in question is called Caitlyn, is wearing a dress, and plainly considers herself[1] a woman seems to me to be doing a poor job at cutting reality at its joints, and I will take the alternative even if that needs some adjustment when I am prescribing drugs for them or contemplating having sex with them.

(The real problem, of course, is that reality doesn't exactly have joints and that so far as it does we're quibbling over which side of the cut a piece of cartilage belongs on. Er, my apologies to any transgender or intersex folks reading this; I would not compare you to a piece of cartilage in other contexts!)

[1] I have attempted to phrase things so as to avoid question-begging via pronouns etc., but here I couldn't find any way that wasn't awfully clumsy. Sorry about that.