If they want to. Whom you date, have sex with, move in with, or marry is a mutual choice between the two of you. But you don’t have to be with anyone you don’t choose to be with.
Writing for the Telegraph, however, Patrick McAleenan describes heterosexual men who won’t date transgender women as fearful, naive, and transphobic. They feel their masculinity threatened. The informal poll on his article shows that McAleenan is writing about three-quarters of heterosexual men.
Likewise, a man choosing to date only cisgender women is no one else’s business. Taking this a step further, no one is entitled to have others find them attractive or to be courted by anyone. Men are not entitled to women, women are not entitled to men, transgender women are not entitled to cisgender men, lesbians are not entitled to other women, and so on.
But more to the point, transphobia isn’t the only reason that some men won’t date transgender women. Not all transgender women have had (or want to have) genital surgery. But a heterosexual, cisgender man will probably be turned off by a transgender woman’s penis. This is no more phobic, however, than a gay man being turned off by a vagina. It’s simply sexual orientation.
Related to this is that transgender women are more likely to be taller and bigger boned than cisgender women, and a heterosexual man might find that unattractive. Here we encounter the issue of body shaming, and shaming men who find certain women unattractive. But I would note that while short men are often made fun of, people who try to shame women for finding short men unattractive are told to respect a woman’s right to have her own preferences and choices.
Finally, a cisgender man might hope to meet a woman he can have biological children with. But this means his partner must be a cisgender woman.
I’ve previously written about identity and setting boundaries, which comes down to your right to do what you want so long as you respect others and don’t impose yourself on them. Shaming men who date transgender women is an illegitimate imposition because a man has a right to date whom he chooses so long as his partner is in full agreement. By the same token, shaming men who refuse to date transgender women is an illegitimate imposition because a man has a right to date whom he chooses so long as his partner is in full agreement.