If anything, transgender is a more obviously wrong-headed argument than Dolezal.
Sex really is binary, and not a spectrum or sliding scale. Substantively everyone is unambiguously male and female.
Race is much more of a spectrum, we are all mixed race, and there is no obvious division. Mixed race siblings can be perceived as completely different from each other despite sharing parentage and background.
So, having said that, if we can fully grasp the offensiveness of a 'white' person approximating and appropriating 'blackness' for themself , we should really get men claiming to be women with perfect clarity.
People claiming they are offended by Dolezal but not by transgender are pure hypocrites.