@MbwaKidogo I've had the intersex argument used on me quite a few times. As far as I can see it's meant to close down the avenue that "there are only 2 sexes, biologically". They are trying to draw parallels to the spectrum of sexuality and make out that you are homophobic.
The implication is that once you accept that intersex people are neither male nor female, then conversely there may be people that appear male or female but in fact are not (or are the opposite). The whole "did you know Jamie Lee Curtjs is in fact male according to her chromosomes, so chromosomes can't tell you anything about sex!"
I have been told:
"biology is much more complex than we thought, we now know there are many sexes, sex is a spectrum"
So when I pointed out that people were in fact not saying they were somewhere on a spectrum but actually claiming to be transitioning from one end of the spectrum to the other, the reaction was "no, they were ALWAYS on the "new" end of the spectrum, it's our perception of how those ends of the spectrum present that has to move with the times."
And when I have tried the "larger gametes" angle they say "oh, so you're saying a woman has to produce gametes, some women are infertile/have had a hysterectomy/ double mastectomy etc etc are you saying they're not a woman??"