No, you are speculating he was born with a vulva. If we all get to speculate, I would suggest that from the information in front of us (46 XY, assumed female at birth so F on passport, very obvious adult male characteristics indicating having been through male puberty) he was likely born with 46XY 5ARD.
From a DSD charity:
If a fetus has 5-AR deficiency (5-ARD), that means that the fetus’s body lacks the enzyme 5-AR. So, early in development, the proto-gonads become testes and they start to make testosterone. But because the enzyme 5-AR is missing, the testosterone doesn’t become dihydrotestosterone. As a result, the fetus’s genitals form more like the typical female’s.
...but are not female genitals, just undeveloped male genitals.
When the child is born, the genitals may look ambiguous or fairly female-typical. (In some cases, children with 5-ARD have been assumed to be females and have been raised female.)
...but are not female, only appear so because of under developed tissue..
At puberty, the child’s testes will make lots more testosterone. Remember now the enzyme 5-AR isn’t necessary for the testosterone to have an affect on sexual maturation at this point. So the child (regardless of which gender the child was raised as) will undergo a male-typical puberty. The phallus will grow to look bigger, more like a penis, the voice will drop as it does in a typical male, the child will develop male-typical face and body hair and male-typical musculature
But this is all speculation. If I was a boxer trying to box in a woman's competition and there was any question as to my eligibility the first thing I would do is get a cheek swab and make the result public. Are these men doing this? Are they heck.