Maybe if the genders were reversed, as in the tfc fan were the female and the impact fan was male, would there be cries of sexism towards men? I think the argument would still be yes if we want to maintain equality. I don't think the act of oral is sexist on its own. It's more the implications that in this poster the one performing oral is beneath the one receiving.
Then again no point in talking hypotheticals. I think the worst part is likely the sexual content in a family environment.