You're assuming that the troon that he's looking at is black and not of a different race.
Its known that people think that those of a different race look alike, so I wouldn't be surprised if that extends to that the men and women of a different race can look similar especially since we know that Asians can clock other Asian troons while most Westerners have trouble telling the difference.
A factor of this is that it is expected of a black woman and ingrained in black women's culture to put a lot of effort into her appearance. This includes hair (goes from curly to straighted, weaves, or hair extensions), makeup, nails, etc. Every black woman has an aunt or grandma who wears girdles. Some girls take it to the extreme and invest in underwear that slims and adds to the body or plastic surgery. This is constant across all economic classes. I have personally never seen it to this amount with white women (exception is rich white women).
The black women that black men want to and are used to seeing are incredibly fabricated. Black men also typically don't want a black woman who's more natural (they want the baddies), therefore this behavior is encouraged in black communities. It's a running joke between a few friends and I that we can only catch white boys with our natural hair/looks because we know that black men are not attracted to it or want a girl that they can brag about to their peers. This means that the average tranny (especially if they are of a different race) can fool a black man if he puts effort into looking like a baddie. Since it's expected of black women to put a lot of effort into their appearance, he just has more material to work with. There are more HSTS in the black community than AGPs anyways, so we already know that they will put effort into passing.