I have also wondered why identifying into a different sex is celebrated but identifying into a different race is offensive.
I listened to DFW (guilty feminist) interview EI and she touched on this point. She said the reason Dolezal identifying as black wasn't ok was because Dolezal wasn't half black to begin with, whereas we are all half male and female, because that's what our parents are!! And then she added the caveat "unless you have 2 biological fathers" - yes, she actually said that.
It was noticable that EI went straight into waffle/fantasy/distraction whenever a potentially difficult issue came up.