JK Rowling really likes to make the villains in her books fat. Umbridge, Vernon, Dudley, Goyle. The characters who embody bullying are nearly always fat. She thinks a person's weight is okay to make fun of if they're a bad person. Rowling fans like to cite Molly as a counterexample, but I think that's missing the point. The fact that the narrator is so mean about these characters' weight makes it clear that weight is on the table as something to make fun of, if Rowling thinks you deserve it. She thinks being fat is shameful, she's just polite when she talks about nice (cis) people.

There's a lot of people who think the same way as Rowling when they talk about Trump.