>If Stallions are now completely biologically female AND they lose their male socialization then whats the difference?
Marionette from the beginning held a strong eye for an eye mentality. Her hatred/fear of a stallion won't allow her to accept a a stallion just because they suddenly turned into into a mare, because they were in fact a stallion at one point and benefited from it. At the very least she would painfully slice off their balls off with rusty scissors and guilt trip them while doing it.