Morgan's personal attacks on women's appearance, using patronising, value laden adjectives like "tacky", "inappropriate", "grotesque", "embarrassing", pollute the social media landscape. There's no basis for his invective except his own disapproval, making his comments seem like old fashioned bullying.
What I will sometimes do is explain that a lot of the work that is being published as YA now would've been published as coming-of-age adult literature twenty years ago, when the YA category didn't really exist as it does now. If J.D. Salinger's Catcher in the Rye were published today, it would be solidly YA. That seems to make them feel better.