How would you know? Unless utterly insane, Upton is aware of being born a biological male and must know that approximating the appearance of a woman will be impossible without extensive surgery.
It's possible for some men to look like a woman from a distance, provided they're well made up - a drag queen can sometimes pull off this illusion using stage make-up, for example. Once you see them close up, however, the illusion is dispelled.
Unless you're Upton, feverishly reading this Mumsnet thread for some form of validation, you're making assumptions.
As for despising trans women, I can only speak for myself. I don't despise transwomen - if someone genuinely has a mental condition which makes them feel that they're the opposite sex then life must terrible for them. However, I despise any male who insists on asserting his supposed 'right' to cause emotional harm to a woman by muscling in on her changing space, particularly under the circumstances outlined by Sandie Peggie.
I can never know how a man wanting to be a woman feels; I do know how a woman feels when she's dealing with a gynaecological problem and needs a space away from the male gaze.