Pretend you see the troon for what it is, a hideous mass of mutilated flesh grasping at a form it fetishises and idealises but cannot understand.
Say you think mtf troons are valid/hot/whatever, and the man who wants to be seen not as a mtf troon but as a woman gets INCREDIBLY Pissed.
It reminds him this is just a gross fetish and men who want men in dresses... that's the best he's gonna get. he's never going to successfully guilt the sexiest woman ever into fucking him.
also, most of them are not into women at all. they were abused as a child by an adult male, and the MTF fetishization is their way of coping with the PTSD.