У нее описан не только Слагхорн, но и хатаскрайник Тонкс. Маглорожденный, который две войны спокойно работал в Мунго. И даже никуда не уезжал. Притом, что у Блэков были к нему претензии.

Ah, Mafalda!” said Umbridge, looking at Hermione.“Travers sent you, did he?”
“Y—yes,” squeaked Hermione.
“Good, you’ll do perfectly well.” Umbridge spoke to the wizard in black and gold. “That’s that problem solved, Minister, if Mafalda can be spared for record-keeping we shall be able to start straightaway.” She consulted her clipboard. “Ten people today and one of them the wife of a Ministry employee!! Tut, tut . . . even here, in the heart of the Ministry!” She stepped into the lift beside Hermione, as did the two wizards who had been listening to Umbridge’s conversation with the Minister. “We’ll go straight down, Mafalda, and you’ll find everything you need in the courtroom.

“Could you please tell us from which witch or wizard you took that wand?”
“T— took?” sobbed Mrs. Cattermole. “I didn’t t-take it from anybody. I b-bought it when I was eleven years old. It—it—it— chose me.”
She cried harder than ever.
Umbridge laughed a soft girlish laugh that made Harry want to attack her.
...
“No,” said Umbridge, “no, I don’t think so, Mrs. Cattermole. Wands only choose witches or wizards. You are not a witch. I have your responses to the questionnaire that was sent to you here— Mafalda, pass them to me.”
...
she continued in a louder voice, flicking through Mrs. Cattermole’s questionnaire, “that the same cannot be said for you. ‘Parents professions: greengrocers.’”
Yaxley laughed jeeringly. Below, the fluffy silver cat patrolled up and down, and the dementors stood waiting in the corners.