"A child, not a choice" literally explains why "my body. my choice" doesn't make sense for abortion; because it's more than a "choice" to kill your child just because it is engulfed by you. "My body. My Choice." actually makes sense for vaccines but is being used to show the irony of the party of "muh body. muh choice" forcing people to take shit experiment vaccine. Perhaps the vaccine is what causes people to lose their sense of irony (and skin falling off and exploding hearts and basically everything but actually preventing the fucking COOF).